9. In which of the following expressions, prime factorisation has been done?
(a) 24 = 2 3 4 (b) 56 = 7 2 2 2
(c) 70 = 2 5 7 (d) 54 = 2 3 9
in factorization, we don't write composite numbers. All the factors should be prime numbers in this method.
(a) 24 = 2 3 4
As we know that 4 is a composite number.
Hence This is not a prime factorization.
b) 56 = 7 2 2 2
In this factorization, all the factors of 56 are prime numbers. There is no composite number.
Hence This is prime factorization.
c) 70 = 2 5 7
In this factorization, all the factors of 70 are prime numbers. There is not a composite number in this process of factorization.
Hence This is prime factorization.
d) 54 = 2 3 9
In this factorization, 54 is written as the product of 2, 3 and 9. In this factorization, 2 and 3 are prime numbers, but 9 is a composite number.
Hence This is not a prime factorization.