Solve (1/3)^-2-(1/3)^-3+(1/7)-2

$$( \frac { 1 } { 3 } ) ^ { - 2 } - ( \frac { 1 } { 3 } ) ^ { - 3 } + ( \frac { 1 } { 7 } ) - 2$$

Evaluate

$$-\frac{139}{7}\approx -19.857142857$$

Solution Steps

Calculate \frac{1}{3} to the power of -2 and get 9.

$$9-\left(\frac{1}{3}\right)^{-3}+\frac{1}{7}-2$$

Calculate \frac{1}{3} to the power of -3 and get 27.

$$9-27+\frac{1}{7}-2$$

Subtract 27 from 9 to get -18.

$$-18+\frac{1}{7}-2$$

Add -18 and \frac{1}{7} to get -\frac{125}{7}.

$$-\frac{125}{7}-2$$

Subtract 2 from -\frac{125}{7} to get -\frac{139}{7}.

$$-\frac{139}{7}$$

Factor

$$-\frac{139}{7} = -19\frac{6}{7} = -19.857142857142858$$