9x^2+21x^2=63

Solution for 9x^2+21x^2=63 equation:

9x^2+21x^2=63

We move all terms to the left:

9x^2+21x^2-(63)=0

We add all the numbers together, and all the variables

30x^2-63=0

a = 30; b = 0; c = -63;
Δ = b2-4ac
Δ = 02-4·30·(-63)
Δ = 7560
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:

$\sqrt{\Delta}=\sqrt{7560}=\sqrt{36*210}=\sqrt{36}*\sqrt{210}=6\sqrt{210}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{210}}{2*30}=\frac{0-6\sqrt{210}}{60}
=-\frac{6\sqrt{210}}{60}
=-\frac{\sqrt{210}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{210}}{2*30}=\frac{0+6\sqrt{210}}{60}
=\frac{6\sqrt{210}}{60}
=\frac{\sqrt{210}}{10}
$