Question

Factor completely: 9x^2+ 42x + 49

(3x + 7)(3x − 7)

(9x − 7)(9x − 7)

(3x + 7)(3x + 7)

(9x + 7)(9x + 7)

Answer 1

the third one, use quadratic formula:\[x=\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a}\]
a=9 b=42 c=49

Answer 2

Hints:
1. The expression has no negative sign means that none of the factors has any negative sign.
That eliminates two choices.
2. The product of the x-terms (3x or 9x) must equal to \(9x^2\) and not \(81x^2\), that eliminates another choice.
So we have eliminated 3 choices and we haven't done any calculations yet.
The last step is the expand the remaining choice to see if you get back the given expression.

Answer 3

Thank You!!!! It really helped.

Answer 4

You're welcome!