X(7x+45)=28

Solution for X(7x+45)=28 equation:

X(7X+45)=28

We move all terms to the left:

X(7X+45)-(28)=0

We multiply parentheses

7X^2+45X-28=0

a = 7; b = 45; c = -28;
Δ = b2-4ac
Δ = 452-4·7·(-28)
Δ = 2809
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2809}=53$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(45)-53}{2*7}=\frac{-98}{14}
=-7
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(45)+53}{2*7}=\frac{8}{14}
=4/7
$