Solve 5x^2+15x-3

$$5 { x }^{ 2 } +15x-3$$

Factor

$$5\left(x-\left(-\frac{\sqrt{285}}{10}-\frac{3}{2}\right)\right)\left(x-\left(\frac{\sqrt{285}}{10}-\frac{3}{2}\right)\right)$$

Steps Using the Quadratic Formula

Quadratic polynomial can be factored using the transformation ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right), where x_{1} and x_{2} are the solutions of the quadratic equation ax^{2}+bx+c=0.

$$5x^{2}+15x-3=0$$

All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.

$$x=\frac{-15±\sqrt{15^{2}-4\times 5\left(-3\right)}}{2\times 5}$$

Square 15.

$$x=\frac{-15±\sqrt{225-4\times 5\left(-3\right)}}{2\times 5}$$

Multiply -4 times 5.

$$x=\frac{-15±\sqrt{225-20\left(-3\right)}}{2\times 5}$$

Multiply -20 times -3.

$$x=\frac{-15±\sqrt{225+60}}{2\times 5}$$

Add 225 to 60.

$$x=\frac{-15±\sqrt{285}}{2\times 5}$$

Multiply 2 times 5.

$$x=\frac{-15±\sqrt{285}}{10}$$

Now solve the equation x=\frac{-15±\sqrt{285}}{10} when ± is plus. Add -15 to \sqrt{285}.

$$x=\frac{\sqrt{285}-15}{10}$$

Divide -15+\sqrt{285} by 10.

$$x=\frac{\sqrt{285}}{10}-\frac{3}{2}$$

Now solve the equation x=\frac{-15±\sqrt{285}}{10} when ± is minus. Subtract \sqrt{285} from -15.

$$x=\frac{-\sqrt{285}-15}{10}$$

Divide -15-\sqrt{285} by 10.

$$x=-\frac{\sqrt{285}}{10}-\frac{3}{2}$$

Factor the original expression using ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Substitute -\frac{3}{2}+\frac{\sqrt{285}}{10} for x_{1} and -\frac{3}{2}-\frac{\sqrt{285}}{10} for x_{2}.

$$5x^{2}+15x-3=5\left(x-\left(\frac{\sqrt{285}}{10}-\frac{3}{2}\right)\right)\left(x-\left(-\frac{\sqrt{285}}{10}-\frac{3}{2}\right)\right)$$

Evaluate

$$5x^{2}+15x-3$$