(7x+2)(4x)=180

Solution for (7x+2)(4x)=180 equation:

(7x+2)(4x)=180

We move all terms to the left:

(7x+2)(4x)-(180)=0

We multiply parentheses

28x^2+8x-180=0

a = 28; b = 8; c = -180;
Δ = b2-4ac
Δ = 82-4·28·(-180)
Δ = 20224
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:

$\sqrt{\Delta}=\sqrt{20224}=\sqrt{256*79}=\sqrt{256}*\sqrt{79}=16\sqrt{79}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-16\sqrt{79}}{2*28}=\frac{-8-16\sqrt{79}}{56}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+16\sqrt{79}}{2*28}=\frac{-8+16\sqrt{79}}{56}
$