X^2+3x=42+4x

Solution for X^2+3x=42+4x equation:

X^2+3X=42+4X

We move all terms to the left:

X^2+3X-(42+4X)=0

We add all the numbers together, and all the variables

X^2+3X-(4X+42)=0

We get rid of parentheses

X^2+3X-4X-42=0

We add all the numbers together, and all the variables

X^2-1X-42=0

a = 1; b = -1; c = -42;
Δ = b2-4ac
Δ = -12-4·1·(-42)
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-13}{2*1}=\frac{-12}{2}
=-6
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+13}{2*1}=\frac{14}{2}
=7
$