question_answer 39)

In which of the following expressions, prime factorisation has been done? (a) \[24=2\times 3\times 4\]       (b) \[56=7\times 2\times 2\times 2\]      (c) \[70=2\times 5\times 7\]       (d) \[54=2\times 3\times 9\]                

Answer:

                (a) We have, \[24=2\times 3\times 4\] Here, 4 is not a prime number. So, number 24 does not have prime factorisation. (b) We have, \[56=7\times 2\times 2\times 2\] Here, 2 and 7 are prime numbers. So, number 56 have prime factorisation. (c) We have, \[70=2\times 5\times 7,\] Here, 2, 5 and 7 all are prime numbers. So, number 70 have prime factorisation. (d) We have, \[54=2\times 3\times 9,\]Here, 9 is not a prime number. So, number 54 does not have prime factorisation.