Question 458858
3x^2 + 48x = -24
: 
Simplify, divide be 3
x^2 + 16x = -8
:
Complete the square
x^2 + 16x + __ = -8
:
To complete the square, divide the coefficient of x by 2 and square it. (8^2)
add to both sides
x^2 + 16x + 64 = -8 + 64
x^2 + 16x + 64 = 56
:
Which is
(x+8)^2 = 56
:
The square root of both sides
x + 8 = +/-{{{sqrt(56)}}}
Factor out the perfect square inside the radical
x + 8 = +/-{{{sqrt(4*14)}}}
extract the {square
x + 8 = +/-{{{2*sqrt(14)}}}
Two solutions
x = {{{-8 + 2sqrt(14)}}}
and 
x = {{{-8 - 2sqrt(14)}}}