Solve 9x^2+7x

$$9 { x }^{ 2 } +7x$$

Factor

$$x\left(9x+7\right)$$

Solution Steps

Factor out x.

$$x\left(9x+7\right)$$

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.

$$9x^{2}+7x=0$$

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.

$$x=\frac{-7±\sqrt{7^{2}}}{2\times 9}$$

Take the square root of 7^{2}.

$$x=\frac{-7±7}{2\times 9}$$

Multiply 2 times 9.

$$x=\frac{-7±7}{18}$$

Now solve the equation x=\frac{-7±7}{18} when ± is plus. Add -7 to 7.

$$x=\frac{0}{18}$$

Divide 0 by 18.

$$x=0$$

Now solve the equation x=\frac{-7±7}{18} when ± is minus. Subtract 7 from -7.

$$x=-\frac{14}{18}$$

Reduce the fraction \frac{-14}{18} to lowest terms by extracting and canceling out 2.

$$x=-\frac{7}{9}$$

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{7}{9} for x_{2}.

$$9x^{2}+7x=9x\left(x-\left(-\frac{7}{9}\right)\right)$$

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

$$9x^{2}+7x=9x\left(x+\frac{7}{9}\right)$$

Add \frac{7}{9} to x by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.

$$9x^{2}+7x=9x\times \frac{9x+7}{9}$$

Cancel out 9, the greatest common factor in 9 and 9.

$$9x^{2}+7x=x\left(9x+7\right)$$

Evaluate

$$x\left(9x+7\right)$$