3(2+5)=3x2+15

Solution for 3(2+5)=3x2+15 equation:

3(2+5)=3x^2+15

We move all terms to the left:

3(2+5)-(3x^2+15)=0

We add all the numbers together, and all the variables

-(3x^2+15)+37=0

We get rid of parentheses

-3x^2-15+37=0

We add all the numbers together, and all the variables

-3x^2+22=0

a = -3; b = 0; c = +22;
Δ = b2-4ac
Δ = 02-4·(-3)·22
Δ = 264
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:

$\sqrt{\Delta}=\sqrt{264}=\sqrt{4*66}=\sqrt{4}*\sqrt{66}=2\sqrt{66}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{66}}{2*-3}=\frac{0-2\sqrt{66}}{-6}
=-\frac{2\sqrt{66}}{-6}
=-\frac{\sqrt{66}}{-3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{66}}{2*-3}=\frac{0+2\sqrt{66}}{-6}
=\frac{2\sqrt{66}}{-6}
=\frac{\sqrt{66}}{-3}
$