Question

Solve this quadratic equation by completing the square.
x2 + 8x = 10

Answer 1

I got the same answer as the first person who answered it correctly.

Answer 2

`x=√(26)-4,\:x=-√(26)-4`

Explanation:

`x^2+8x=10`

Write this equation in the form of:
`x^2+2ax+a^2=\left(x+a\right)^2`

Solve for a:

`2ax=8x`

`(2ax)/(2x)=(8x)/(2x)`

`a=4`

Add
`a^2=4^2` to both sides:

`x^2+8x+4^2=10+4^2`

`\left(x+4\right)^2=26`

`x+4=√(26)`

`x+4-4=√(26)-4`

`x=√(26)-4`

`x+4=-√(26)`

`x+4-4=-√(26)-4`

`x=-√(26)-4`