21x^2-25x-10=4

Solution for 21x^2-25x-10=4 equation:

21x^2-25x-10=4

We move all terms to the left:

21x^2-25x-10-(4)=0

We add all the numbers together, and all the variables

21x^2-25x-14=0

a = 21; b = -25; c = -14;
Δ = b2-4ac
Δ = -252-4·21·(-14)
Δ = 1801
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{-(-25)-\sqrt{1801}}{2*21}=\frac{25-\sqrt{1801}}{42}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+\sqrt{1801}}{2*21}=\frac{25+\sqrt{1801}}{42}
$