Question

Solve using quadratic formula x squared -2x-8=0

Answer 1

x² - 2x - 8 = 0
x = -(-2) +/- √((-2)² - 4(1)(-8))
2(1)
x = 2 +/- √(4 + 32)
2
x = 2 +/- √(36)
2
x = 2 +/- 6
2
x = 1 +/- 3
x = 1 + 3 x = 1 - 3
x = 4 x = -2

Answer 2

`x= (-b\pm √(b^2-4ac) )/(2a)` for the equation
`ax^2+bx+c`

Your question is
`x^2-2x-8=0`

So
`a=1 \\b=-2\\c=-8`

So plug in your numbers:

`x= (-(-2)\pm √((-2)^2-4(1)(-8)) )/(2(1))`

Simplify:

`x= (2\pm √(4-(-32)) )/(2)`

Simplify a little more:

`(2\pm6)/(2)`

So our answer is

`x= (2+ 6 )/(2) = 4\\x= (2- 6 )/(2)=-2`

So
`x=4, x=-2`