70x-25x^2=40

Solution for 70x-25x^2=40 equation:

70x-25x^2=40

We move all terms to the left:

70x-25x^2-(40)=0

a = -25; b = 70; c = -40;
Δ = b2-4ac
Δ = 702-4·(-25)·(-40)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-30}{2*-25}=\frac{-100}{-50}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+30}{2*-25}=\frac{-40}{-50}
=4/5
$