how to complete the square of x(x+18)=19

Question

anonymous · Answer

First distribute, you get

x^2 = 18x = 19

To complete the square, you take (1/2) of the coefficient of x, and then square that number. Add that number to both sides of the equation.

The coefficient of x is 18, so (1/2) of 18 = 9; and 9^2 = 81.

So we add 81 to both sides of the equation.

x^2 + 18x + 81 = 19 + 81

The left side is a perfect square....

(x+ 9)^2 = 100

so x+ 9 = +/- sqrt (100)

x + 9 = +/- 10

subtract 9 from both sides, you get

x = 1 or -19.

anonymous · Answer

First line should read x^2 + 18x = 19