Question

Solve the quadratic by completing the square.

Answer 1

Hey there!

x^2-18x+79=0

To complete the square, you need to take half of 18, and square it. You have to have complete squares for C for this to work.

-18/2= -9

-9^2= 81

(x^2-18x+81)-81+79=0

The factor is 9, and the -18 is negative.

(x-9)^2 -81+79=0

Add the numbers.

-81+79= -2

(x-9)^2=-2

Now, unsquare both sides.

√(x-9)^2= √-2

Negative square roots do not exist, so it is an imaginary number. Put tha tin front of the 2.

(x-9)=± i√2

x= -9±i√2 <=== the answer

I hope this helps!

~kaikers