Find the Cube of : 3a- 2b

Find the cube of : 3a- 2b

Sum

( a - b )³ = a³ - 3ab( a - b ) - b³
( 3a - 2b )³ = (3a)³ - 3 x 3a x 2b( 3a - 2b) - (2b)³
= 27a³ - 18ab( 3a - 2b ) - 8b³
= 27a³ - 54a²b + 36ab² - 8b³

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Chapter 4 Expansions (Including Substitution)
Exercise 4 (B) | Q 1.1 | Page 60

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