Simplify: x + 7/x^2 + 4x - 21

A. 1/x - 3; where x doesn't equal 3, 7
B. x - 3: where x doesn't equal 3
C. 1/x - 7; where x doesn't equal 7
D. x - 7

Thanks.

Question

Simplify: x + 7/x^2 + 4x - 21

A. 1/x - 3; where x doesn't equal 3, 7
B. x - 3: where x doesn't equal 3
C. 1/x - 7; where x doesn't equal 7
D. x - 7

Thanks.

pfenn1 · Answer

$$\frac{x + 7}{x^2 + 4x - 21}$$ Factor the denominator such that $$x^2+4x-21=(x+a)(x+b)$$where (a + b) = 4 and ab = -21.  I'm guessing one of the factors will be (x + 7) so it can cancel with the numerator.

anonymous · Answer

I got C. Is that right? Thanks for your answer by the way.

pfenn1 · Answer

No, I didn't get C.  How did you get that?

anonymous · Answer

$$\frac{x+7}{x^2 +4x-21}\ \frac{x+7}{(x+7    )( x-3)}\ \frac{  \cancel{x+7}    }{(\cancel{x+7})( x-3)}\ \ anzwer : \ \frac{1}{x-3} $$