Solve 47x+131x^2=0

$$47 x + 131 x ^ { 2 } = 0$$

Solve for x

$$x=-\frac{47}{131}\approx -0.358778626$$

$$x=0$$

Steps Using Factoring

Factor out x.

$$x\left(47+131x\right)=0$$

To find equation solutions, solve x=0 and 47+131x=0.

$$x=0 x=-\frac{47}{131}$$

Steps Using the Quadratic Formula

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.

$$131x^{2}+47x=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 131 for a, 47 for b, and 0 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-47±\sqrt{47^{2}}}{2\times 131}$$

Take the square root of 47^{2}.

$$x=\frac{-47±47}{2\times 131}$$

Multiply 2 times 131.

$$x=\frac{-47±47}{262}$$

Now solve the equation x=\frac{-47±47}{262} when ± is plus. Add -47 to 47.

$$x=\frac{0}{262}$$

Divide 0 by 262.

$$x=0$$

Now solve the equation x=\frac{-47±47}{262} when ± is minus. Subtract 47 from -47.

$$x=-\frac{94}{262}$$

Reduce the fraction \frac{-94}{262} to lowest terms by extracting and canceling out 2.

$$x=-\frac{47}{131}$$

The equation is now solved.

$$x=0 x=-\frac{47}{131}$$

Steps for Completing the Square

Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.

$$131x^{2}+47x=0$$

Divide both sides by 131.

$$\frac{131x^{2}+47x}{131}=\frac{0}{131}$$

Dividing by 131 undoes the multiplication by 131.

$$x^{2}+\frac{47}{131}x=\frac{0}{131}$$

Divide 0 by 131.

$$x^{2}+\frac{47}{131}x=0$$

Divide \frac{47}{131}, the coefficient of the x term, by 2 to get \frac{47}{262}. Then add the square of \frac{47}{262} to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$x^{2}+\frac{47}{131}x+\left(\frac{47}{262}\right)^{2}=\left(\frac{47}{262}\right)^{2}$$

Square \frac{47}{262} by squaring both the numerator and the denominator of the fraction.

$$x^{2}+\frac{47}{131}x+\frac{2209}{68644}=\frac{2209}{68644}$$

Factor x^{2}+\frac{47}{131}x+\frac{2209}{68644}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.

$$\left(x+\frac{47}{262}\right)^{2}=\frac{2209}{68644}$$

Take the square root of both sides of the equation.

$$\sqrt{\left(x+\frac{47}{262}\right)^{2}}=\sqrt{\frac{2209}{68644}}$$

Simplify.

$$x+\frac{47}{262}=\frac{47}{262} x+\frac{47}{262}=-\frac{47}{262}$$

Subtract \frac{47}{262} from both sides of the equation.

$$x=0 x=-\frac{47}{131}$$