Question 1013184
From another website comes this...
This is the original equation.	ax^2 + bx + c = 0

Move the loose number to the other side.	ax^2 + bx = –c

Divide through by whatever is multiplied on the squared term.
Take half of the x-term, and square it. Add the squared term to both sides.

x^2 + (b/a)x + (b^2/4a^2) = –(c/a) + (b^2/4a^2)

Simplify on the right-hand side; in this case, simplify by converting to a common denominator.	

x^2 + (b/a)x + (b^2/4a^2) = –(4ac/4a^2) + (b^2/4a^2)

Convert the left-hand side to square form (and do a bit more simplifying on the right).	

(x + b/2a)^2 = (b^2 – 4ac)/4a^2

Square-root both sides, remembering to put the "±" on the right.	

x + b/2a = ± sqrt(b^2 – 4ac)/2a

Solve for "x =", and simplify as necessary.	

x = [ –b ± sqrt(b^2 – 4ac) ] / 2a