9x*7x=80

Solution for 9x*7x=80 equation:

9x*7x=80

We move all terms to the left:

9x*7x-(80)=0

Wy multiply elements

63x^2-80=0

a = 63; b = 0; c = -80;
Δ = b2-4ac
Δ = 02-4·63·(-80)
Δ = 20160
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:

$\sqrt{\Delta}=\sqrt{20160}=\sqrt{576*35}=\sqrt{576}*\sqrt{35}=24\sqrt{35}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-24\sqrt{35}}{2*63}=\frac{0-24\sqrt{35}}{126}
=-\frac{24\sqrt{35}}{126}
=-\frac{4\sqrt{35}}{21}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+24\sqrt{35}}{2*63}=\frac{0+24\sqrt{35}}{126}
=\frac{24\sqrt{35}}{126}
=\frac{4\sqrt{35}}{21}
$