(0.29x^2)+21x=72.9

Solution for (0.29x^2)+21x=72.9 equation:

(0.29x^2)+21x=72.9

We move all terms to the left:

(0.29x^2)+21x-(72.9)=0

We add all the numbers together, and all the variables

21x+(0.29x^2)-72.9=0

We get rid of parentheses

0.29x^2+21x-72.9=0

a = 0.29; b = 21; c = -72.9;
Δ = b2-4ac
Δ = 212-4·0.29·(-72.9)
Δ = 525.564
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{-(21)-\sqrt{525.564}}{2*0.29}=\frac{-21-\sqrt{525.564}}{0.58}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+\sqrt{525.564}}{2*0.29}=\frac{-21+\sqrt{525.564}}{0.58}
$