to solve by completing the square what value should you add to each side of the equation x^2+20x=-8

Question

campbell_st · Answer

a perfect square is 

$$(x +b)^2 = x^2 + 2bx + b^2$$

so halve to middle term, then square it... 

then add the value to both sides of the equation.

wolf1728 · Answer

To complete the square we have to have the x² term have no exponent and move the non-x term to the right side of the equation.(The equation was already given this way).
Then we take the coefficient of x (20) which we divide by 2 square then add it to both sides
20/2 = 10 and 10² = 100

x^2 + 20x + 100 = 92 
(x+10) * (x+10) = 92
taking the square root of both sides
x +10 = sqrt(92)
x = 9.5916630466 -10
x = -0.4083369534

campbell_st · Answer

just a quick point... you will have 2 solutions to your problem not 1

as you are looking at 

$$x + 10 = \pm \sqrt{92}$$

wolf1728 · Answer

campbell_st
Unbelievable - I went to the trouble of typing a rather detailed explanation of completing the square - and I only gave half the answer.
Good catch!!