M=x^2+6x

Solution for M=x^2+6x equation:

=M^2+6M

We move all terms to the left:

-(M^2+6M)=0

We get rid of parentheses

-M^2-6M=0

We add all the numbers together, and all the variables

-1M^2-6M=0

a = -1; b = -6; c = 0;
Δ = b2-4ac
Δ = -62-4·(-1)·0
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$M_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$M_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$M_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-6}{2*-1}=\frac{0}{-2}
=0
$
$M_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+6}{2*-1}=\frac{12}{-2}
=-6
$