16x^2+9x^2=6561

Solution for 16x^2+9x^2=6561 equation:

16x^2+9x^2=6561

We move all terms to the left:

16x^2+9x^2-(6561)=0

We add all the numbers together, and all the variables

25x^2-6561=0

a = 25; b = 0; c = -6561;
Δ = b2-4ac
Δ = 02-4·25·(-6561)
Δ = 656100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{656100}=810$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-810}{2*25}=\frac{-810}{50}
=-16+1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+810}{2*25}=\frac{810}{50}
=16+1/5
$