Start by factoring -2 out of all three terms:
-8x2 + 54x + 140 => -2(4x^2 - 27x - 70)
Applying the quadratic formula: b^2 - 4ac becomes (-27)^2 - 4(4)(-70), or 1849.
Because this discriminant is +, this quadratic has two real, unequal roots. They are:
-(-27) plus or minus sqrt(1849) 27 plus or minus 43
x = ------------------------------------------------ = ---------------------------------- =
2(4) 8
= {70/8, -2}
Thus, -8x2 + 54x + 140 factors into -2(x+2)(4x-35)
