4x(2x-10)=140

Solution for 4x(2x-10)=140 equation:

4x(2x-10)=140

We move all terms to the left:

4x(2x-10)-(140)=0

We multiply parentheses

8x^2-40x-140=0

a = 8; b = -40; c = -140;
Δ = b2-4ac
Δ = -402-4·8·(-140)
Δ = 6080
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{6080}=\sqrt{64*95}=\sqrt{64}*\sqrt{95}=8\sqrt{95}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-8\sqrt{95}}{2*8}=\frac{40-8\sqrt{95}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+8\sqrt{95}}{2*8}=\frac{40+8\sqrt{95}}{16}
$