X2+8X+15=(x+3)

Solution for X2+8X+15=(x+3) equation:

X2+8X+15=(X+3)

We move all terms to the left:

X2+8X+15-((X+3))=0

We add all the numbers together, and all the variables

X^2+8X-((X+3))+15=0


We calculate terms in parentheses: -((X+3)), so:

(X+3)

We get rid of parentheses

X+3

Back to the equation:

-(X+3)


We get rid of parentheses

X^2+8X-X-3+15=0

We add all the numbers together, and all the variables

X^2+7X+12=0

a = 1; b = 7; c = +12;
Δ = b2-4ac
Δ = 72-4·1·12
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1}=1$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-1}{2*1}=\frac{-8}{2}
=-4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+1}{2*1}=\frac{-6}{2}
=-3
$