Solve -2x^2+30x

$$-2 { x }^{ 2 } +30x$$

Factor

$$2x\left(15-x\right)$$

Solution Steps

Factor out 2.

$$2\left(-x^{2}+15x\right)$$

Consider -x^{2}+15x. Factor out x.

$$x\left(-x+15\right)$$

Rewrite the complete factored expression.

$$2x\left(-x+15\right)$$

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.

$$-2x^{2}+30x=0$$

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.

$$x=\frac{-30±\sqrt{30^{2}}}{2\left(-2\right)}$$

Take the square root of 30^{2}.

$$x=\frac{-30±30}{2\left(-2\right)}$$

Multiply 2 times -2.

$$x=\frac{-30±30}{-4}$$

Now solve the equation x=\frac{-30±30}{-4} when ± is plus. Add -30 to 30.

$$x=\frac{0}{-4}$$

Divide 0 by -4.

$$x=0$$

Now solve the equation x=\frac{-30±30}{-4} when ± is minus. Subtract 30 from -30.

$$x=-\frac{60}{-4}$$

Divide -60 by -4.

$$x=15$$

Factor the original expression using ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Substitute 0 for x_{1} and 15 for x_{2}.

$$-2x^{2}+30x=-2x\left(x-15\right)$$

Evaluate

$$2x\left(15-x\right)$$