Question

6. simplify (i) (3x + 4y)3 +(3x—4y)3
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Answer 1

(3x + 4y)³ +(3x - 4y)³

a³ + b³ = (a+b)³ - 3ab(a+b)

(3x + 4y + 3x - 4y)³ - 3(3x + 4y)(3x - 4y)( 3x +4y + 3x -4y)

(6x)³ - 3((3x)² - (4y)²)(6x)

216x³ - (18x)(9x² - 16y²)

216x³ - (162 x³ - 288xy²)

216x³ - 162 x³ + 288xy²

54x³ + 288xy² (Answer)