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ICSE-VIII-Mathematics

04: Cubes and Cube Roots Class 8 Maths

with Solutions -
Qstn# A-4-i Prvs-QstnNext-Qstn
  • #4-i
    3/7 (ii) 8/9 (iii) 10/13 (iv) 1 2/7 (v) 2 ½
    Ans : 3/7= (3/7)3= (3 × 3 × 3)/(7 × 7 × 7)= 27/343 (ii) 8/9= (8/9)3= (8 × 8 × 8)/(9 × 9 × 9)= 512/729 (iii) 10/13= (10/13)3= (10 × 10 × 10)/(13 × 13 × 13)= 1000/2197 (iv) 1 2/7= (1 2/7)3= {(1 × 7 + 2)/7}3= (9/7)3
    = (9 × 9 × 9)/(7 × 7 × 7)= 729/343= 2 43/343 (v) 2½= (2 1/2)3= (5/2)3
    = (5 × 5 × 5)/(2 × 2 × 2)= 125/8= 15 5/8
  • #4-ii
    8/9
    Ans : 8/9= (8/9)3= (8 × 8 × 8)/(9 × 9 × 9)= 512/729
  • #4-iii
    10/13
    Ans : 10/13= (10/13)3= (10 × 10 × 10)/(13 × 13 × 13)= 1000/2197
  • #4-iv
    1 2/7
    Ans : 1 2/7= (1 2/7)3= {(1 × 7 + 2)/7}3= (9/7)3
    = (9 × 9 × 9)/(7 × 7 × 7)= 729/343= 2 43/343
  • #4-v
    2 ½
    Ans : 2½= (2 1/2)3= (5/2)3
    = (5 × 5 × 5)/(2 × 2 × 2)= 125/8= 15 5/8