## Introductory Algebra for College Students (7th Edition)

The coefficient of x is -2. Adding the square of half the coefficient of x creates a perfect square. $(-2\div2)^2=(-1)^2=1$ $x^2-2x=8$ Add the square of half the coefficient of x to each side of the equation. $x^2-2x+1=8+1$ Simplify. $x^2-2x+1=9$ Factor the polynomial. $(x-1)^2=9$ Take the square root of each side. $\sqrt{(x-1)^2}=\sqrt 9$ Simplify. $x-1=3$ Add 1 to each side. $x-1+1=3+1$ Simplify. $x=4$