Question

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

Answer 1

x = -3 , - 15

Explanation:

Given:

x² + 18x + 45 = 0

Solve:

`x_(1,\:2)=(-18\pm √(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)=(-18\pm \:12)/(2\cdot \:1)`

Separate the solution

`x_1=(-18+12)/(2\cdot \:1),\:x_2=(-18-12)/(2\cdot \:1)`

`x_1=(-18+12)/(2\cdot \:1)=-3`

`x_2=(-18-12)/(2\cdot \:1)=-15`

Thus, the answer are:

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

Kavinsky