Question

PLEASE HELP

Solve the equation, x2 - 2x - 8 = 0 by completing the square .

a. x = 4 or x = -2

b. x = 4 or x = 2

c. x = -4 or x = -2

d. x = -4 or x = 2

Answer 1

A

Explanation:

Completing the square requires a quadratic in
`ax^2+bx=c` form. Once in this form, calculate
`((b)/(2))^2`.

Here x2 - 2x - 8 = 0 converts to x2 - 2x = 8. So b = -2.

`((b)/(2))^2=((-2)/(2))^2=1`

Add 1 to both sides.

x2 - 2x + 1 = 8 + 1

(x -1)^2 = 9

Square root both sides.

x-1 = 3 x - 1 = -3

x = 4 x = -2

This is the solution.