Q. 723.6( 10 Votes )

Find the value of:

(a) 70

(b) 77 ÷ 77

(c) (–7)2 × 7 – 6 – 8

(d) (20 + 30 + 40) (40 – 30 – 20)

(e) 2 × 3 × 4 ÷ 20 × 30 × 40

(f) (80 – 20) × (80 + 20)

Answer :

(a) We have the law of Indices as follows:


a0 = 1


Where a = any integer


70 = 1


(b) According to Law of indices,


ax ÷ ay = a (x - y)


Here in the question,


a = 7


x = 7


y = 7


x - y = 7 - 7


= 0


77 ÷ 77 = 70 = 1


(c) (–7)2 × 7 – 6 – 8

= (–7)14-14


= (–7)0


= 1


(d) (20 + 30 + 40) (40 – 30 – 20) = (1 + 1 + 1) × (1-1-1)


= 3 × -1


= -3


(e) Let us evaluate the terms separately,


2 × 3 × 4 = 6 × 4


= 24


20 × 30 × 40 = 1 × 1 × 1


= 1


2 × 3 × 4 ÷ 20 × 30 × 40 = 24 / 1


= 24


(f) (80 – 20) × (80 + 20)

= (1 – 1) × (1 + 1)


= 0 × 1


= 0

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