Question

solve by completing the square: x^2+18x+45=0

Answer 1

Answer:

 x = -3 , - 15

Step-by-step explanation:

Given:

x² + 18x + 45 = 0

Solve:

$x_{1,\:2}=\frac{-18\pm \sqrt{18^2-4\cdot \:1\cdot \:45}}{2\cdot \:1}$

Simplify

$-18\pm \sqrt{18^2-4\cdot \:1\cdot \:45=12$

$x_{1,\:2}=\frac{-18\pm \:12}{2\cdot \:1}$

Separate the solution

$x_1=\frac{-18+12}{2\cdot \:1},\:x_2=\frac{-18-12}{2\cdot \:1}$

$x_1=\frac{-18+12}{2\cdot \:1}=-3$

$x_2=\frac{-18-12}{2\cdot \:1}=-15$

Thus, the answer are:

$x=-3,\:x=-15$

Kavinsky