### Home > AC > Chapter 11 > Lesson 11.1.5 > Problem11-56

11-56.

Simplify the rational expression below. What values can $x$ not be?

$\frac{3x^2+11x-20}{2x^2+11x+5}$

The denominator cannot be equal to zero.What value(s) of x would make the denominator zero?

$\left(2x + 1\right)\left(x + 5\right) = 0$

$2x^{2} + 11x + 5 = 0$

$x ≠ −0.5 \text{ or } −5$

Factor both the numerator and the denominator.

$\frac { ( 3 x - 4 ) ( x + 5 ) } { ( 2 x + 1 ) ( x + 5 ) }$

Look for $1$.

$\frac { ( 3 x - 4 ) } { ( 2 x + 1 ) }$