Solve 1(x)=5/x+1

$$1(x) = \frac{ 5 }{ x+1 }$$

Solve for x

$$x = \frac{\sqrt{21} - 1}{2} \approx 1.791287847$$

$$x=\frac{-\sqrt{21}-1}{2}\approx -2.791287847$$

Steps Using the Quadratic Formula

Variable x cannot be equal to -1 since division by zero is not defined. Multiply both sides of the equation by x+1.

$$1x\left(x+1\right)=5$$

Use the distributive property to multiply 1x by x+1.

$$x^{2}+1x=5$$

Subtract 5 from both sides.

$$x^{2}+1x-5=0$$

Reorder the terms.

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

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 1 for b, and -5 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-1±\sqrt{1^{2}-4\left(-5\right)}}{2}$$

Square 1.

$$x=\frac{-1±\sqrt{1-4\left(-5\right)}}{2}$$

Multiply -4 times -5.

$$x=\frac{-1±\sqrt{1+20}}{2}$$

Add 1 to 20.

$$x=\frac{-1±\sqrt{21}}{2}$$

Now solve the equation x=\frac{-1±\sqrt{21}}{2} when ± is plus. Add -1 to \sqrt{21}.

$$x=\frac{\sqrt{21}-1}{2}$$

Now solve the equation x=\frac{-1±\sqrt{21}}{2} when ± is minus. Subtract \sqrt{21} from -1.

$$x=\frac{-\sqrt{21}-1}{2}$$

The equation is now solved.

$$x=\frac{\sqrt{21}-1}{2} x=\frac{-\sqrt{21}-1}{2}$$

Steps for Completing the Square

Variable x cannot be equal to -1 since division by zero is not defined. Multiply both sides of the equation by x+1.

$$1x\left(x+1\right)=5$$

Use the distributive property to multiply 1x by x+1.

$$x^{2}+1x=5$$

Reorder the terms.

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

Divide 1, the coefficient of the x term, by 2 to get \frac{1}{2}. Then add the square of \frac{1}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$x^{2}+x+\left(\frac{1}{2}\right)^{2}=5+\left(\frac{1}{2}\right)^{2}$$

Square \frac{1}{2} by squaring both the numerator and the denominator of the fraction.

$$x^{2}+x+\frac{1}{4}=5+\frac{1}{4}$$

Add 5 to \frac{1}{4}.

$$x^{2}+x+\frac{1}{4}=\frac{21}{4}$$

Factor x^{2}+x+\frac{1}{4}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.

$$\left(x+\frac{1}{2}\right)^{2}=\frac{21}{4}$$

Take the square root of both sides of the equation.

$$\sqrt{\left(x+\frac{1}{2}\right)^{2}}=\sqrt{\frac{21}{4}}$$

Simplify.

$$x+\frac{1}{2}=\frac{\sqrt{21}}{2} x+\frac{1}{2}=-\frac{\sqrt{21}}{2}$$

Subtract \frac{1}{2} from both sides of the equation.

$$x=\frac{\sqrt{21}-1}{2} x=\frac{-\sqrt{21}-1}{2}$$