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
