10u^2+5u-15=0

Solution for 10u^2+5u-15=0 equation:

10u^2+5u-15=0

a = 10; b = 5; c = -15;
Δ = b2-4ac
Δ = 52-4·10·(-15)
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-25}{2*10}=\frac{-30}{20}
=-1+1/2
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+25}{2*10}=\frac{20}{20}
=1
$