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James19142 James19142 is offline

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math question

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Oct 22nd, 2009

how do i solve this problem
r+5(r-2)=28
3(r+4)+5(r+2)=102

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Grn Xtrm

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Oct 22nd, 2009

This question seemingly has nothing to do with c++. In the future dont post math related questions in the programming forums.
As for your problem, what does the question ask you to do? Do you have to solve for the variable r?

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Oct 22nd, 2009

1st) Read post 1, although if you PM, someone that knows a little math, he might help you.

2)

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
Let A = r+5(r-2)=28
Let B = 3(r+4)+5(r+2)=102 
 
 
//Break down A
A = r+5(r-2) = 28
= r + 5r - 10 = 28 //distributive rule
= 6r - 10 = 20 //add like trms
= 6r = 20 + 10  //remember switching numbers to the opposite sides mean change its operatorion from + to minus, * to / and vice-versa
so, 6r = 20 + 10,
6r = 30
r = 30/6 = 15/3 = 5
Let A = r+5(r-2)=28
Let B = 3(r+4)+5(r+2)=102 


//Break down A
A = r+5(r-2) = 28
= r + 5r - 10 = 28 //distributive rule
= 6r - 10 = 20 //add like trms
= 6r = 20 + 10  //remember switching numbers to the opposite sides mean change its operatorion from + to minus, * to / and vice-versa
so, 6r = 20 + 10,
6r = 30
r = 30/6 = 15/3 = 5

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
//Break down of B
Let B = 3(r+4)+5(r+2)=102 
 
B = 3r + 12 + 10r + 20 = 102 //Distributive property
=  3r + 10r + 12 + 20 = 102 // re-arrange like terms
= 13r + 32 = 102 //add like terms
 = 13r = 102 - 32 //bring together like terms
 = 13r = 70
 = r = 70/13
//Break down of B
Let B = 3(r+4)+5(r+2)=102 

B = 3r + 12 + 10r + 20 = 102 //Distributive property
=  3r + 10r + 12 + 20 = 102 // re-arrange like terms
= 13r + 32 = 102 //add like terms
 = 13r = 102 - 32 //bring together like terms
 = 13r = 70
 = r = 70/13

Help with Code Tags

(Toggle Plain Text)

1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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Dave Sinkula Dave Sinkula is offline

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Oct 22nd, 2009

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Originally Posted by firstPerson

Help with Code Tags

(Toggle Plain Text)
A = r+5(r-2) = 28
= r + 5r - 10 = 28 //distributive rule
= 6r - 10 = 20 //add like trms
A = r+5(r-2) = 28 = r + 5r - 10 = 28 //distributive rule = 6r - 10 = 20 //add like trms

Where'd the 28 go and the 20 come from?

Last edited by Dave Sinkula; Oct 22nd, 2009 at 10:20 am.

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Oct 22nd, 2009

Also with B: this B = 3r + 12 + 10r + 20 = 102 //Distributive property is completely wrong. I have no idea what you're trying to do here.
Look, if r(B)=70/13=5.38... (according to you) then if you substitute 'r' with 5.38... in the original formula, you should get 102; which you don't.

the answer to B is 10. But I'm not going to show the math here, because the OP needs to learn to do his/her own damn homework.

Last edited by niek_e; Oct 22nd, 2009 at 10:50 am.

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firstPerson firstPerson is offline

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Oct 23rd, 2009

Lol, I was high when I posted that, sorry.

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1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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niek_e

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Oct 23rd, 2009

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Originally Posted by firstPerson

Lol, I was high when I posted that, sorry.

You shouldn't drink and drive and you should smoke and do math. That's how people come up with stuff like the Large Hadron Collider: very dangerous

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iamthwee

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Oct 23rd, 2009

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Originally Posted by firstPerson

1st) Read post 1, although if you PM, someone that knows a little math, he might help you.

2)
Help with Code Tags

C++ Syntax (Toggle Plain Text)
Let A = r+5(r-2)=28
Let B = 3(r+4)+5(r+2)=102 
 
 
//Break down A
A = r+5(r-2) = 28
= r + 5r - 10 = 28 //distributive rule
= 6r - 10 = 20 //add like trms
= 6r = 20 + 10  //remember switching numbers to the opposite sides mean change its operatorion from + to minus, * to / and vice-versa
so, 6r = 20 + 10,
6r = 30
r = 30/6 = 15/3 = 5
Let A = r+5(r-2)=28 Let B = 3(r+4)+5(r+2)=102 //Break down A A = r+5(r-2) = 28 = r + 5r - 10 = 28 //distributive rule = 6r - 10 = 20 //add like trms = 6r = 20 + 10 //remember switching numbers to the opposite sides mean change its operatorion from + to minus, * to / and vice-versa so, 6r = 20 + 10, 6r = 30 r = 30/6 = 15/3 = 5
Help with Code Tags

C++ Syntax (Toggle Plain Text)
//Break down of B
Let B = 3(r+4)+5(r+2)=102 
 
B = 3r + 12 + 10r + 20 = 102 //Distributive property
=  3r + 10r + 12 + 20 = 102 // re-arrange like terms
= 13r + 32 = 102 //add like terms
 = 13r = 102 - 32 //bring together like terms
 = 13r = 70
 = r = 70/13
//Break down of B Let B = 3(r+4)+5(r+2)=102 B = 3r + 12 + 10r + 20 = 102 //Distributive property = 3r + 10r + 12 + 20 = 102 // re-arrange like terms = 13r + 32 = 102 //add like terms = 13r = 102 - 32 //bring together like terms = 13r = 70 = r = 70/13

I thought you purposely gave him a dud answer so he would hand it in. Well done you had me fooled.

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Reprise

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Oct 23rd, 2009

niek_e is correct about the second equation having r = 10. I didn't see anyone give a correct answer for the first, so I will: r = 19/3.

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Originally Posted by niek_e

You shouldn't drink and drive and you should smoke and do math. That's how people come up with stuff like the Large Hadron Collider: very dangerous

Ha. I refuse to subscribe to the theory that the LHC could end the world.

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#10

Oct 23rd, 2009

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Originally Posted by iamthwee

I thought you purposely gave him a dud answer so he would hand it in. Well done you had me fooled.

Maybe, I don't remember what I was thinking at that time.

Help with Code Tags

(Toggle Plain Text)

1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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