Move right part of the equation to
left part with negative sign.
The equation is transformed from
$$2 x^{2} - 3 x + 15 = 11 x - 5$$
to
$$\left(- 11 x + 5\right) + \left(2 x^{2} - 3 x + 15\right) = 0$$
This equation is of the form
$$a\ x^2 + b\ x + c = 0$$
A quadratic equation can be solved using the discriminant
The roots of the quadratic equation:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where $D = b^2 - 4 a c$ is the discriminant.
Because
$$a = 2$$
$$b = -14$$
$$c = 20$$
, then
$$D = b^2 - 4\ a\ c = $$
$$\left(-1\right) 2 \cdot 4 \cdot 20 + \left(-14\right)^{2} = 36$$
Because D > 0, then the equation has two roots.
$$x_1 = \frac{(-b + \sqrt{D})}{2 a}$$
$$x_2 = \frac{(-b - \sqrt{D})}{2 a}$$
or
$$x_{1} = 5$$
Simplify$$x_{2} = 2$$
Simplify