2x^2-0.7x-1=0

Solution for 2x^2-0.7x-1=0 equation:

2x^2-0.7x-1=0

a = 2; b = -0.7; c = -1;
Δ = b2-4ac
Δ = -0.72-4·2·(-1)
Δ = 8.49
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{-(-0.7)-\sqrt{8.49}}{2*2}=\frac{0.7-\sqrt{8.49}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.7)+\sqrt{8.49}}{2*2}=\frac{0.7+\sqrt{8.49}}{4}
$