8x^2-10x-42=0

Solution for 8x^2-10x-42=0 equation:

8x^2-10x-42=0

a = 8; b = -10; c = -42;
Δ = b2-4ac
Δ = -102-4·8·(-42)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-38}{2*8}=\frac{-28}{16}
=-1+3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+38}{2*8}=\frac{48}{16}
=3
$