Question

Using suitable identity factorise 32a3 – 72a.

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Answer 1

Step-by-step explanation:

32a3 +108b3

= 4(8a3 + 27b3)

= 4((2a)3 + (3b)3) [Using a3 + b3 = (a + b)(a2 - ab + b2)]

= 4 [(2a + 3b)((2a)2 - 2a x 3b + (3b)2)]

= 4(2a + 3b)(4a2 - 6ab + 9b2)

∴ 32a3 +108b3 = 4(2a + 3b)(4a2 - 6ab + 9b2 )