Algebra Needed

[Tresha91203]

You must also know that P+I=A.

A=500(1+0.1x). so
P+I=500(1+0.1x)
500+100=500+50x
600=500+50x
100=50x
2=x

2 years (if it's *annual*). If they ask how many months, convert to 24.

Great I plugged in my numbers and came up with 28. I suppose it could be 2.3 years, but I didn't do any converting, so it shouldn't have come out months.
I give up on this formula.

Post the problem. You can rewrite the same formula this way (solved for t) if it helps:. t = (1/r)(A/P - 1)

I would never in God's name remember that or be able to explain why it works to a student. lol

It's ok, lol. Math, like music, is a language. I do this all day as an academic tutor. It's basically like translating.

 

[Tresha91203]

You must also know that P+I=A.

A=500(1+0.1x). so
P+I=500(1+0.1x)
500+100=500+50x
600=500+50x
100=50x
2=x

2 years (if it's *annual*). If they ask how many months, convert to 24.

Great I plugged in my numbers and came up with 28. I suppose it could be 2.3 years, but I didn't do any converting, so it shouldn't have come out months.
I give up on this formula.

Post the problem. You can rewrite the same formula this way (solved for t) if it help

Again you need people not these people

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

 

[OldLady]

That's not to say Tresha and Moon and Fueri aren't doing it right--they just can't explain it in a way I, the Math Moron, can understand it. Simple procedural steps. Oh so simple.

Check the wording of the problem. It may be a "gotcha" problem. The formula is correct. For instance, is there any wording that would indicate you need montly numbers rather than annual?

The wording is exactly the same as what I posted, but the numbers are:
George is going to borrow $600 at 12% APR simple interest. He wants his total interest payment to be at most $100. What length of time can he take out the loan if that is the most he wants to pay on interest?

P+I=P(1+0.12t)
700=600(1+0.12t)
700=600+72t
100=72t
1.39=t

Thanks, Tesh. I'm following you through 700=600+72t
then you lost me.
How did you get 100=72t?
From there, I get how you got 1.39.
It was that step from line 3 to line 4 that lost me.

I need to isolate t so that it is alone ... t=
In order to do that, I have to get rid of the +600 attached to 72t, then get rid of *72 so that t is alone. Whatever I remove from one side of the equation, I MUST also remove from the other side of the equation or the equation is different.

700 = 600 + 72t I need to get t by itself
-600 -600
-------------------------------
100 = 72t
To get t alone, I have to undo 72*t. To reverse t*72, I divide by 72....Both sides
100/72=72*t÷72
On the right, the 72's cancel out, leaving t by itself

I had forgotten you could subtract on both sides of the equation. I thought you could only divide or multiply and still have an equivalent.
Thx!
I believe I can work this through now.

 

[Dekster]

You must also know that P+I=A.

A=500(1+0.1x). so
P+I=500(1+0.1x)
500+100=500+50x
600=500+50x
100=50x
2=x

2 years (if it's *annual*). If they ask how many months, convert to 24.

Great I plugged in my numbers and came up with 28. I suppose it could be 2.3 years, but I didn't do any converting, so it shouldn't have come out months.
I give up on this formula.

Post the problem. You can rewrite the same formula this way (solved for t) if it help

Again you need people not these people

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

 

[Tresha91203]

Check the wording of the problem. It may be a "gotcha" problem. The formula is correct. For instance, is there any wording that would indicate you need montly numbers rather than annual?

The wording is exactly the same as what I posted, but the numbers are:
George is going to borrow $600 at 12% APR simple interest. He wants his total interest payment to be at most $100. What length of time can he take out the loan if that is the most he wants to pay on interest?

P+I=P(1+0.12t)
700=600(1+0.12t)
700=600+72t
100=72t
1.39=t

Thanks, Tesh. I'm following you through 700=600+72t
then you lost me.
How did you get 100=72t?
From there, I get how you got 1.39.
It was that step from line 3 to line 4 that lost me.

I need to isolate t so that it is alone ... t=
In order to do that, I have to get rid of the +600 attached to 72t, then get rid of *72 so that t is alone. Whatever I remove from one side of the equation, I MUST also remove from the other side of the equation or the equation is different.

700 = 600 + 72t I need to get t by itself
-600 -600
-------------------------------
100 = 72t
To get t alone, I have to undo 72*t. To reverse t*72, I divide by 72....Both sides
100/72=72*t÷72
On the right, the 72's cancel out, leaving t by itself

I had forgotten you could subtract on both sides of the equation. I thought you could only divide or multiply and still have an equivalent.
Thx!
I believe I can work this through now.

Excellent. Just holler if you hit a roadblock.

 

[Tresha91203]

Great I plugged in my numbers and came up with 28. I suppose it could be 2.3 years, but I didn't do any converting, so it shouldn't have come out months.
I give up on this formula.

Post the problem. You can rewrite the same formula this way (solved for t) if it help

Again you need people not these people

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

 

[Dekster]

Post the problem. You can rewrite the same formula this way (solved for t) if it help

Again you need people not these people

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

Then give them the OP problem as a bonus on the final exam and let us know what percentage did it and how of those who did, what percentage got it right.

 

[OldLady]

Post the problem. You can rewrite the same formula this way (solved for t) if it help

Again you need people not these people

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

That it is truly frightening to me.
It always took me longer than anyone else to cotton on when new things were introduced in Math. Once I got it, I was fine, but it was a long struggle. Back then in the dark ages, they didn't separate out the boneheads like me and put us in a slower group. So I was always lost within 5 minutes of algebra class. I was a high honors student in everything else, but I couldn't pass algebra. I had tutors, I repeated the class, my mother prayed. It took a 65 to pass my Algebra 2 final and graduate high school with a Regents diploma--or any diploma. They gave me a 65, and I'm sure I got extra points for spelling my name right. Maybe my brain just wasn't ready for it. I don't know.

 

[Dekster]

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

That it is truly frightening to me.
It always took me longer than anyone else to cotton on when new things were introduced in Math. Once I got it, I was fine, but it was a long struggle. Back then in the dark ages, they didn't separate out the boneheads like me and put us in a slower group. So I was always lost within 5 minutes of algebra class. I was a high honors student in everything else, but I couldn't pass algebra. I had tutors, I repeated the class, my mother prayed. It took a 65 to pass my Algebra 2 final and graduate high school with a Regents diploma--or any diploma. They gave me a 65, and I'm sure I got extra points for spelling my name right. Maybe my brain just wasn't ready for it. I don't know.

I think sometimes the reputation of algebra etc causes students to push back when faced with it. All that grade, really algebra isn't much different than everything that came before. You are just replacing the _____ from third grade with X or Y so 2+_____=5 becomes 2+X=5.

 

[eagle1462010]

You must also know that P+I=A.

A=500(1+0.1x). so
P+I=500(1+0.1x)
500+100=500+50x
600=500+50x
100=50x
2=x

2 years (if it's *annual*). If they ask how many months, convert to 24.

That's what I got and how I did it. Same answer. You know the total of 600 so you plug and chug and figure APR as yearly

 

[OldLady]

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

That it is truly frightening to me.
It always took me longer than anyone else to cotton on when new things were introduced in Math. Once I got it, I was fine, but it was a long struggle. Back then in the dark ages, they didn't separate out the boneheads like me and put us in a slower group. So I was always lost within 5 minutes of algebra class. I was a high honors student in everything else, but I couldn't pass algebra. I had tutors, I repeated the class, my mother prayed. It took a 65 to pass my Algebra 2 final and graduate high school with a Regents diploma--or any diploma. They gave me a 65, and I'm sure I got extra points for spelling my name right. Maybe my brain just wasn't ready for it. I don't know.

I think sometimes the reputation of algebra etc causes students to push back when faced with it. All that grade, really algebra isn't much different than everything that came before. You are just replacing the _____ from third grade with X or Y so 2+_____=5 becomes 2+X=5.

Shut up, Deks.

 

[eagle1462010]

In Algebra whatever you do to one side of the equal sign.........you must do to the other side...............whether add or subtract to make the value you are trying to move zero......to move to the other side...........

so 600 = 500 + 8(x).........you would subtract 500 from both sides to move it.

600 -500 = 500 - 500 +8x
100 = 0 + 8x
100 = 8x
100/8 = x
12.5 = x

 

[Tresha91203]

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

That it is truly frightening to me.
It always took me longer than anyone else to cotton on when new things were introduced in Math. Once I got it, I was fine, but it was a long struggle. Back then in the dark ages, they didn't separate out the boneheads like me and put us in a slower group. So I was always lost within 5 minutes of algebra class. I was a high honors student in everything else, but I couldn't pass algebra. I had tutors, I repeated the class, my mother prayed. It took a 65 to pass my Algebra 2 final and graduate high school with a Regents diploma--or any diploma. They gave me a 65, and I'm sure I got extra points for spelling my name right. Maybe my brain just wasn't ready for it. I don't know.

Don't feel bad. I had the same issue with World History AP. Teacher just gave it to me out of pity.

 

[Tresha91203]

bones, I am beginning to think this is true. There has to be someone here who can do this, though--they tried from 9th grade on to teach me how.

It isn't really 9th grade algebra for a problem like this. OP has moved over into to the trig/calculus area.

It's 9th grade algebra now. Students factor polynomials in 9th grade now, too.

This is beyond factoring polynomials. It is differentiation. If students are doing derivatives standard in 9th grade algebra now, it certainly is not showing up in math scores on standardized testing.

My 7th grade students learn the simple interest formula and how to solve for each variable. School is very different today

Then give them the OP problem as a bonus on the final exam and let us know what percentage did it and how of those who did, what percentage got it right.

Here's 7th grade math games for simple interest word problems.

Simple Interest - Grade 7 - Practice with Math Games

IXL also has a whole strand on it in 7th grade.

 

[eagle1462010]

I was always good in math and science. History did ok..........was enlash and biology that cooked me..........lol

Math always seemed easy to me. lol