7(2x^2-9x-10)=0

Solution for 7(2x^2-9x-10)=0 equation:

7(2x^2-9x-10)=0

We multiply parentheses

14x^2-63x-70=0

a = 14; b = -63; c = -70;
Δ = b2-4ac
Δ = -632-4·14·(-70)
Δ = 7889
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{7889}=\sqrt{49*161}=\sqrt{49}*\sqrt{161}=7\sqrt{161}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-63)-7\sqrt{161}}{2*14}=\frac{63-7\sqrt{161}}{28}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-63)+7\sqrt{161}}{2*14}=\frac{63+7\sqrt{161}}{28}
$