use the quadratic formula.

2x2 + 8x = - 1

3 answers

put it in standard format:

2x2 + 8x + 1=0

x= (-8 +-sqrt(64-8))/4

you do it.
to indicate exponents on this forum we usually say ..

2x^2 + 8x = - 1
2x^2 + 8x + 1 = 0

here a=2, b=8, c=1
and
x =(-b ± √(b^2 - 4ac))/(2a)
= (-8 ± √(64-8))/4
= (-4 ± √14)/2
2X2+8x=-1
4+8x=-1
8x=-1-4
x=-5/8
x=-0.625