4x+5=x(x+3)

Solution for 4x+5=x(x+3) equation:

4x+5=x(x+3)

We move all terms to the left:

4x+5-(x(x+3))=0


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

x(x+3)

We multiply parentheses

x^2+3x

Back to the equation:

-(x^2+3x)


We get rid of parentheses

-x^2+4x-3x+5=0

We add all the numbers together, and all the variables

-1x^2+x+5=0

a = -1; b = 1; c = +5;
Δ = b2-4ac
Δ = 12-4·(-1)·5
Δ = 21
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{21}}{2*-1}=\frac{-1-\sqrt{21}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{21}}{2*-1}=\frac{-1+\sqrt{21}}{-2}
$