Solve 5x+9x^2

$$5 x + 9 x ^ { 2 }$$

Factor

$$x\left(9x+5\right)$$

Solution Steps

Factor out x.

$$x\left(5+9x\right)$$

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.

$$9x^{2}+5x=0$$

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.

$$x=\frac{-5±\sqrt{5^{2}}}{2\times 9}$$

Take the square root of 5^{2}.

$$x=\frac{-5±5}{2\times 9}$$

Multiply 2 times 9.

$$x=\frac{-5±5}{18}$$

Now solve the equation x=\frac{-5±5}{18} when ± is plus. Add -5 to 5.

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

Divide 0 by 18.

$$x=0$$

Now solve the equation x=\frac{-5±5}{18} when ± is minus. Subtract 5 from -5.

$$x=-\frac{10}{18}$$

Reduce the fraction \frac{-10}{18} to lowest terms by extracting and canceling out 2.

$$x=-\frac{5}{9}$$

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{5}{9} for x_{2}.

$$9x^{2}+5x=9x\left(x-\left(-\frac{5}{9}\right)\right)$$

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

$$9x^{2}+5x=9x\left(x+\frac{5}{9}\right)$$

Add \frac{5}{9} to x by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.

$$9x^{2}+5x=9x\times \frac{9x+5}{9}$$

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

$$9x^{2}+5x=x\left(9x+5\right)$$

Evaluate

$$x\left(9x+5\right)$$