Question

Solve the following quadratic by

completing the square.
y = x2 + 2x – 6
x =
[?]+)

Answer 1

x = - 1 ±
`√(7)`

Explanation:

let y = 0

x² + 2x - 6 = 0 ( add 6 to both sides )

x² + 2x = 6

To complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(1)x + 1 = 6 + 1

(x + 1)² = 7 ( take the square root of both sides )

x + 1 = ±
`√(7)` ( subtract 1 from both sides )

x = - 1 ±
`√(7)` , that is

x = - 1 +
`√(7)` , x = - 1 -
`√(7)`