0.10x+0.25x(x+7)=5.25

Solution for 0.10x+0.25x(x+7)=5.25 equation:

0.10x+0.25x(x+7)=5.25

We move all terms to the left:

0.10x+0.25x(x+7)-(5.25)=0

We add all the numbers together, and all the variables

0.10x+0.25x(x+7)-5.25=0

We multiply parentheses

0x^2+0.10x+0x-5.25=0

We add all the numbers together, and all the variables

x^2+1.1x-5.25=0

a = 1; b = 1.1; c = -5.25;
Δ = b2-4ac
Δ = 1.12-4·1·(-5.25)
Δ = 22.21
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{-(1.1)-\sqrt{22.21}}{2*1}=\frac{-1.1-\sqrt{22.21}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.1)+\sqrt{22.21}}{2*1}=\frac{-1.1+\sqrt{22.21}}{2}
$