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I'm having some trouble and I've not been very good at math, so I need some help with...

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shoopuff | Student, Grade 9 | eNotes Newbie

Posted August 15, 2010 at 9:46 AM via web

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I'm having some trouble and I've not been very good at math, so I need some help with (7x+2)3+8x

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neela | High School Teacher | Valedictorian

Posted August 15, 2010 at 10:11 AM (Answer #1)

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To simplify (7x+2)3+8x.

Multiplication is didtributive over addtion. So (7x+2)3 = 7x*3+2*3= 7*3*x+2*3 =21x+6, as 7x*3 = 7*3*x = 21x by commutative property of multiplication.

Therefore (7x+2)3+8x = 21x+2+8x =21x+8x+6 = (21+8)x +6  =29x+6.

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hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted August 15, 2010 at 10:59 AM (Answer #2)

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(7x + 2)3 + 8x

Let us use the distribution method :

We know that:

(a+ b)*c = a*c + b*c

==> (7x+2)*3 + 8x = 7x*3 + 2*3 + 8x

==> 21x + 6 + 8x

Now group similar:

==> 29x + 6

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jeyaram | Student, Undergraduate | Valedictorian

Posted August 17, 2010 at 10:10 PM (Answer #3)

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(7x+2)3+8x=7*3*x+2*3+8*x

=21x+6+8x

=29x+6

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lynn30k | High School Teacher | (Level 3) Associate Educator

Posted August 15, 2010 at 9:58 AM (Answer #4)

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Remember PEMDAS--parentheses, exponents, multiply, divide, add, subtract, in that order. Look at the expression you want to simplify. The first thing to do is multiply both of the variables in the parenthesis by the 3 on the outside. Usually, the 3 would be before the parenthesis, but it doesn't matter here, because you want to multiply before you do anything with the 8x. So:

7x times 3 = 21x      2 times 3 = 6     8x stays 8x

Now you can combine the terms that have 'x'   21x+8x=29x, so your expression becomes 21x + 6

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atyourservice | TA , Grade 10 | Valedictorian

Posted June 26, 2014 at 6:39 AM (Answer #5)

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(7x+2)3+8x

the first step is to distribute the 3 to the numbers inside the parentheses:

21x + 6 + 8x

now combine like terms (8x and 21x)

29x + 6

and that's the answer

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givingiswinning | TA , Grade 10 | Valedictorian

Posted August 15, 2014 at 11:54 PM (Answer #6)

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(7x+2)3+8x

21x + 6 + 8x

29x + 6

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