Question

Solve the quadratic equation by completing the square.

x^2 +4x- 9=0
first, choose the appropriate form and fill in the blanks with the correct numbers.
then, solve the equation. if there is more than one solution, separate them with commas.

Answer 1

x = -2 ±√13

Explanation:

To complete the square, take the middle term bx and divide it in two. Then take the square.

x^2 + 4x - 9 has bx = 4x. Take 4/2 = 2. Square 2^2 = 4.

Now to finish completing the square add 4 to each side.

x^2 + 4x - 9 = 0

x^2 + 4x + 4 - 9 = 4

(x+2)^2 -9 = 4

Add 9 to both sides and take the square root of each side to solve.

(x+2)^2 = 13

(x+2) = ± √13

x = -2 ±√13