Question 34285
x^2-x-20=0
(x^2-x   = 20
Complete the square on the left side and maintain the equality as follows:
x^2-x+(1/2)^2  = 20 + (1/2)^2
Factor the left side and simplify the right to get:
(x-(1/2))^2 = 81/4
Take the sqrt of both sides to get;
x-(1/2) = +9/2  or x-(1/2)= -9/2
Then x=10/2=5  or x=-8/2= -4
Cheers,
Stan H.