CLASS 8 MATHS CHAPTER 7-CUBES AND CUBE ROOTS
Exercise 7.1 Question 1. Which of the following numbers are not perfect cubes:(i)216(ii)128(iii)1000(iv)100(v)46656 Solution : (i)216Prime factors of 216 = 2×2×2×3×3×3Here all factors are in groups of 3’s (in triplets)Therefore, 216 is a perfect cube number.(ii) 128Prime factors of 128= 2×2×2×2×2×2×2Here one factor 2 does not appear in a 3’s group.Therefore, 128 is not a …