Question

(3a - 5b) (9a² + 15ab + 25b²)

Answer 1

$Given \: (3a-5b)(9a^{2}+15ab+25b^{2})$

$= (3a-5b)[ (3a)^{2} + (3a)(5b) + (5b)^{2} \\= (3a)^{3} - (5b)^{3}$

/* By algebraic identity */

$\boxed{\pink{ (x-y)(x^{2}+xy+y^{2}) = x^{3}-y^{3} }}$

$= 27a^{3} - 125b^{3}$

Therefore.,

$\red{ (3a-5b)(9a^{2}+15ab+25b^{2}) }$

$\green {= 27a^{3} - 125b^{3} }$

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