3x(7x-15)=14

Solution for 3x(7x-15)=14 equation:

3x(7x-15)=14

We move all terms to the left:

3x(7x-15)-(14)=0

We multiply parentheses

21x^2-45x-14=0

a = 21; b = -45; c = -14;
Δ = b2-4ac
Δ = -452-4·21·(-14)
Δ = 3201
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{-(-45)-\sqrt{3201}}{2*21}=\frac{45-\sqrt{3201}}{42}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-45)+\sqrt{3201}}{2*21}=\frac{45+\sqrt{3201}}{42}
$