10x^2+10x+1=21

Solution for 10x^2+10x+1=21 equation:

10x^2+10x+1=21

We move all terms to the left:

10x^2+10x+1-(21)=0

We add all the numbers together, and all the variables

10x^2+10x-20=0

a = 10; b = 10; c = -20;
Δ = b2-4ac
Δ = 102-4·10·(-20)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-30}{2*10}=\frac{-40}{20}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+30}{2*10}=\frac{20}{20}
=1
$