SOLUTION: Hi, I need to multiply (3x+9)^2...my answer is 3x^2+27x+81...am I right???

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Hi, I need to multiply (3x+9)^2...my answer is 3x^2+27x+81...am I right???      Log On


   



Question 84719: Hi, I need to multiply (3x+9)^2...my answer is 3x^2+27x+81...am I right???
Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
.
%283x%2B9%29%5E2
.
This translates to:
.
%283x+%2B+9%29%2A%283x+%2B+9%29
.
Take the 3x in the first set of parentheses and multiply it by both terms in the second set
of parentheses. The result is:
.
3x%2A3x+%2B+3x%2A9
.
Each of these answers is as follows:
.
9x%5E2+%2B+27x
.
Next take the second term in the first set of parentheses. This second term is +9. Multiply
it by both of the terms in the second set of parentheses. The result is:
.
9%2A3x+%2B+9%2A9
.
And the two answers are:
.
27x+%2B+81
.
Now add the two answers that you got:
.
9x%5E2+%2B+27x+%2B+27x+%2B+81
.
You can then add the two 27x terms and you get the final answer:
.
9x%5E2+%2B+54x+%2B+81
.
That's the answer you should have gotten. Hopefully this will help you to find what you
did incorrectly to get two of the terms wrong in your answer.
.