Question

(1,34×10⁴)×(2,3×10³)

Answer 1

x 13.2

Class 7

Maths Question 1.

Using laws of e×ponents, simplify and write the answer in e×ponential form:

(i) 32 × 34 × 38

(ii) 615 ÷ 610

(iii) a3 × a2

(iv) 7x × 72

(v) (52)3 ÷ 53

(vi) 25 × 55

(vii) a4 × b4

(viii) (34)3

(ix) (220 ÷ 215) × 23

(x) 8t ÷ 82

Solution:

(i) 32 × 34 × 38 = 32+4+8 = 314 [am ÷ an = am+n]

(ii) 615 ÷ 610 = 615-10 = 65 [am ÷ an = am-n]

(iii) a3 × a2 = a3+2 = a5 [am × an = am+n]

(iv) 7x × 72 = 7x+2 [am × an = am+n]

(v) (52)3 ÷ 53 = 52×3 ÷ 53 = 56 ÷ 53 = 56-3 = 53 [(a3)n = amn, am ÷ an = am-n]

(vi) 25 × 55 = (2 × 5)5 = 105 [am × bm = (ab)m]

(vii) a4 × b4 = (ab)4 [am × bm = (ab)4]

(ix) (220 ÷ 215) × 23 = 220-15 × 23

=25 × 23 = 25+3 = 28

(x) 8t ÷ 82 = 8t-2 [am ÷ an = am-n