Question

solve for the solutionsm set of the following expressions using completing the square:

x squared + 9x + 18=0
2x squared + 12x + 4 =0
x squared + 6x-8=0
4 x squared - x - 3=0

what will be the answer .. ?

Answer 1

x^2 + 9x + 18 = 0

you need to calculate (9/2)^2 and add to both sides of the equation

(x^2 + 9x + 81/4) = 81/4 - 18

or

(x + 9/2)^2 = 9/4

take the square root of both sides

\[x + \frac{9}{2} = \pm \frac{3}{2}\]

all you need to do is subtract 9/2 from both sides for the solutions