0=49x^2+28x-15

Solution for 0=49x^2+28x-15 equation:

0=49x^2+28x-15

We move all terms to the left:

0-(49x^2+28x-15)=0

We add all the numbers together, and all the variables

-(49x^2+28x-15)=0

We get rid of parentheses

-49x^2-28x+15=0

a = -49; b = -28; c = +15;
Δ = b2-4ac
Δ = -282-4·(-49)·15
Δ = 3724
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:

$\sqrt{\Delta}=\sqrt{3724}=\sqrt{196*19}=\sqrt{196}*\sqrt{19}=14\sqrt{19}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-14\sqrt{19}}{2*-49}=\frac{28-14\sqrt{19}}{-98}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+14\sqrt{19}}{2*-49}=\frac{28+14\sqrt{19}}{-98}
$