x(x*2)=35

Solution for x(x*2)=35 equation:

x(x*2)=35

We move all terms to the left:

x(x*2)-(35)=0

We add all the numbers together, and all the variables

x(+x*2)-35=0

We multiply parentheses

2x^2-35=0

a = 2; b = 0; c = -35;
Δ = b2-4ac
Δ = 02-4·2·(-35)
Δ = 280
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:

$\sqrt{\Delta}=\sqrt{280}=\sqrt{4*70}=\sqrt{4}*\sqrt{70}=2\sqrt{70}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{70}}{2*2}=\frac{0-2\sqrt{70}}{4}
=-\frac{2\sqrt{70}}{4}
=-\frac{\sqrt{70}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{70}}{2*2}=\frac{0+2\sqrt{70}}{4}
=\frac{2\sqrt{70}}{4}
=\frac{\sqrt{70}}{2}
$