# Evaluate

(i) {(1/3)^{−1 }− (1/4)^{−1}}^{−1 }(ii) (5/8)^{−7}× (8/5)^{−4}

**Solution:**

(i) {(1/3)^{−1 }− (1/4)^{−1}}^{−1}

According to the rules of exponents,

(a/b)^{−m} = (b/a)^{m}

{(1/3)^{−1 }− (1/4)^{−1}}^{−1}

= (3^{1 }− 4^{1})^{−1 }

= (3 − 4)^{−1}

= (−1)^{−1}

= (−1/1)^{1}= −1

(ii) (5/8)^{−7}× (8/5)^{−4}

According to the rules of exponents,

We know that, (a/b)^{−m} = (b/a)^{m}

(5/8)^{−7}× (8/5)^{−4}

= (8/5)^{7 }× (8/5)^{−4}

= (8/5)^{3 } [Since, a^{m}/a^{n} = a^{m - n}]

= 512/125

**Video Solution:**

## Evaluate (i) {(1/3)^{−1 }− (1/4)^{−1}}^{−1 }(ii) (5/8)^{−7}× (8/5)^{−4}

### Class 8 Maths NCERT Solutions - Chapter 12 Exercise 12.1 Question 6

**Summary:**

The value of the following expressions are (i) {(1/3)^{−1 }− (1/4)^{−1}}^{-1} = -1^{ }(ii) (5/8)^{−7}× (8/5)^{−4} = 512/125