a2+15a+6=7-a

Solution for a2+15a+6=7-a equation:

a2+15a+6=7-a

We move all terms to the left:

a2+15a+6-(7-a)=0

We add all the numbers together, and all the variables

a2+15a-(-1a+7)+6=0

We add all the numbers together, and all the variables

a^2+15a-(-1a+7)+6=0

We get rid of parentheses

a^2+15a+1a-7+6=0

We add all the numbers together, and all the variables

a^2+16a-1=0

a = 1; b = 16; c = -1;
Δ = b2-4ac
Δ = 162-4·1·(-1)
Δ = 260
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{260}=\sqrt{4*65}=\sqrt{4}*\sqrt{65}=2\sqrt{65}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2\sqrt{65}}{2*1}=\frac{-16-2\sqrt{65}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2\sqrt{65}}{2*1}=\frac{-16+2\sqrt{65}}{2}
$