Explanation:
4x² + 12x + 8 = 0
this has the same solutions as
x² + 3x + 2 = 0
as we simply divided everything by 4. 0/4 = 0.
the general solution to such a quadratic equation
ax² + bx + c = 0
is
x = (-b ± sqrt(b² - 4ac))/(2a)
in our case that is
x = (-3 ± sqrt(3² - 4×1×2))/(2×1) =
= (-3 ± sqrt(9 - 8))/2 = (-3 ± sqrt(1))/2
x1 = (-3 + 1)/2 = -2/2 = -1
x2 = (-3 - 1)/2 = -4/2 = -2
so, the 2 solutions are
x = -1
or
x = -2