Question

Solve x2 - 7x = -13.

Answer 1

by completing the square and using the quadratic formula

Answer 2

x^2 - 7x = -13
(x - 7/2)^2 = -13 + (7/2)^2
Simplify the right.
Take square roots on both sides and solve for x.

Answer 3

To complete the square for the general quadratic equation: ax^2 + bx + c = 0
Make the leading coefficient 1 by dividing throughout by a
x^2 +(b/a)x + (c/a) = 0
Take the constant to the other side
x^2 +(b/a)x = -(c/a)
{ x + (b/(2a)) }^2 = -(c/a) + (b/(2a))^2

So b/2a will be the term that will go inside the square.