Question

What is the value of the rational expression 2x2+5x+9/x2+2x-1 when x=-2

Answer 1

The answer is -7.

In order to find this, try evaluating the numerator and denominator separately and then divide afterwards.

Numerator:
2x^2 + 5x + 9
2(-2)^2 + 5(-2) + 9
2(4) - 10 + 9
8 - 1
7

Denominator:
x^2 + 2x - 1
(-2)^2 + 2(-2) - 1
4 - 4 - 1
-1

Now divide the answers
7/-1 = -7

Answer 2

The value of given expression at x=-2 is -7.

Explanation:

The given expression is

`(2x^2+5x+9)/(x^2+2x-1)`

Substitute x=-2 in the above expression.

`(2(-2)^2+5(-2)+9)/((-2)^2+2(-2)-1)`

Solve the squares and brackets.

`(2(4)-10+9)/(4-4-1)`

`(8-1)/(-1)`

`(7)/(-1)`

`-7`

Therefore the value of given expression at x=-2 is -7.