Solve n^2+n/6=n-1

$$\frac { n ^ { 2 } + n } { 6 } = n - 1$$

Solve for n

$$n=2$$

$$n=3$$

Steps Using Factoring

Multiply both sides of the equation by 6.

$$n^{2}+n=6n-6$$

Subtract 6n from both sides.

$$n^{2}+n-6n=-6$$

Combine n and -6n to get -5n.

$$n^{2}-5n=-6$$

Add 6 to both sides.

$$n^{2}-5n+6=0$$

To solve the equation, factor n^{2}-5n+6 using formula n^{2}+\left(a+b\right)n+ab=\left(n+a\right)\left(n+b\right). To find a and b, set up a system to be solved.

$$a+b=-5 ab=6$$

Since ab is positive, a and b have the same sign. Since a+b is negative, a and b are both negative. List all such integer pairs that give product 6.

$$-1,-6 -2,-3$$

Calculate the sum for each pair.

$$-1-6=-7 -2-3=-5$$

The solution is the pair that gives sum -5.

$$a=-3 b=-2$$

Rewrite factored expression \left(n+a\right)\left(n+b\right) using the obtained values.

$$\left(n-3\right)\left(n-2\right)$$

To find equation solutions, solve n-3=0 and n-2=0.

$$n=3 n=2$$

Steps Using Factoring By Grouping

Multiply both sides of the equation by 6.

$$n^{2}+n=6n-6$$

Subtract 6n from both sides.

$$n^{2}+n-6n=-6$$

Combine n and -6n to get -5n.

$$n^{2}-5n=-6$$

Add 6 to both sides.

$$n^{2}-5n+6=0$$

To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as n^{2}+an+bn+6. To find a and b, set up a system to be solved.

$$a+b=-5 ab=1\times 6=6$$

Since ab is positive, a and b have the same sign. Since a+b is negative, a and b are both negative. List all such integer pairs that give product 6.

$$-1,-6 -2,-3$$

Calculate the sum for each pair.

$$-1-6=-7 -2-3=-5$$

The solution is the pair that gives sum -5.

$$a=-3 b=-2$$

Rewrite n^{2}-5n+6 as \left(n^{2}-3n\right)+\left(-2n+6\right).

$$\left(n^{2}-3n\right)+\left(-2n+6\right)$$

Factor out n in the first and -2 in the second group.

$$n\left(n-3\right)-2\left(n-3\right)$$

Factor out common term n-3 by using distributive property.

$$\left(n-3\right)\left(n-2\right)$$

To find equation solutions, solve n-3=0 and n-2=0.

$$n=3 n=2$$

Steps Using the Quadratic Formula

Multiply both sides of the equation by 6.

$$n^{2}+n=6n-6$$

Subtract 6n from both sides.

$$n^{2}+n-6n=-6$$

Combine n and -6n to get -5n.

$$n^{2}-5n=-6$$

Add 6 to both sides.

$$n^{2}-5n+6=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, -5 for b, and 6 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$n=\frac{-\left(-5\right)±\sqrt{\left(-5\right)^{2}-4\times 6}}{2}$$

Square -5.

$$n=\frac{-\left(-5\right)±\sqrt{25-4\times 6}}{2}$$

Multiply -4 times 6.

$$n=\frac{-\left(-5\right)±\sqrt{25-24}}{2}$$

Add 25 to -24.

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

Take the square root of 1.

$$n=\frac{-\left(-5\right)±1}{2}$$

The opposite of -5 is 5.

$$n=\frac{5±1}{2}$$

Now solve the equation n=\frac{5±1}{2} when ± is plus. Add 5 to 1.

$$n=\frac{6}{2}$$

Divide 6 by 2.

$$n=3$$

Now solve the equation n=\frac{5±1}{2} when ± is minus. Subtract 1 from 5.

$$n=\frac{4}{2}$$

Divide 4 by 2.

$$n=2$$

The equation is now solved.

$$n=3 n=2$$

Steps for Completing the Square

Multiply both sides of the equation by 6.

$$n^{2}+n=6n-6$$

Subtract 6n from both sides.

$$n^{2}+n-6n=-6$$

Combine n and -6n to get -5n.

$$n^{2}-5n=-6$$

Divide -5, the coefficient of the x term, by 2 to get -\frac{5}{2}. Then add the square of -\frac{5}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$n^{2}-5n+\left(-\frac{5}{2}\right)^{2}=-6+\left(-\frac{5}{2}\right)^{2}$$

Square -\frac{5}{2} by squaring both the numerator and the denominator of the fraction.

$$n^{2}-5n+\frac{25}{4}=-6+\frac{25}{4}$$

Add -6 to \frac{25}{4}.

$$n^{2}-5n+\frac{25}{4}=\frac{1}{4}$$

Factor n^{2}-5n+\frac{25}{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}.

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

Take the square root of both sides of the equation.

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

Simplify.

$$n-\frac{5}{2}=\frac{1}{2} n-\frac{5}{2}=-\frac{1}{2}$$

Add \frac{5}{2} to both sides of the equation.

$$n=3 n=2$$