Solve 18x^2+66x

$$18 x ^ { 2 } + 66 x$$

Factor

$$6x\left(3x+11\right)$$

Solution Steps

Factor out 6.

$$6\left(3x^{2}+11x\right)$$

Consider 3x^{2}+11x. Factor out x.

$$x\left(3x+11\right)$$

Rewrite the complete factored expression.

$$6x\left(3x+11\right)$$

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.

$$18x^{2}+66x=0$$

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.

$$x=\frac{-66±\sqrt{66^{2}}}{2\times 18}$$

Take the square root of 66^{2}.

$$x=\frac{-66±66}{2\times 18}$$

Multiply 2 times 18.

$$x=\frac{-66±66}{36}$$

Now solve the equation x=\frac{-66±66}{36} when ± is plus. Add -66 to 66.

$$x=\frac{0}{36}$$

Divide 0 by 36.

$$x=0$$

Now solve the equation x=\frac{-66±66}{36} when ± is minus. Subtract 66 from -66.

$$x=-\frac{132}{36}$$

Reduce the fraction \frac{-132}{36} to lowest terms by extracting and canceling out 12.

$$x=-\frac{11}{3}$$

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 -\frac{11}{3} for x_{2}.

$$18x^{2}+66x=18x\left(x-\left(-\frac{11}{3}\right)\right)$$

Simplify all the expressions of the form p-\left(-q\right) to p+q.

$$18x^{2}+66x=18x\left(x+\frac{11}{3}\right)$$

Add \frac{11}{3} to x by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.

$$18x^{2}+66x=18x\times \frac{3x+11}{3}$$

Cancel out 3, the greatest common factor in 18 and 3.

$$18x^{2}+66x=6x\left(3x+11\right)$$

Evaluate

$$6x\left(3x+11\right)$$