If 2a - 3b = 3 and ab = 2,find the value of 8a cube - 27 b cube
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2a-3b=3
cubing both sides
(2a-3b)³=3³
8a³-27b³+3(2a)²(-3b) + 3(2a)(-3b)²=27
8a³-27b³+3(2a)(-3b){2a-3b}=27
8a³-27b³-18ab{3}=27
8a³-27b³-18(2)(3)=27
8a³-27b³-108=27
8a³-27b³=108+27
8a³-27b³=135
cubing both sides
(2a-3b)³=3³
8a³-27b³+3(2a)²(-3b) + 3(2a)(-3b)²=27
8a³-27b³+3(2a)(-3b){2a-3b}=27
8a³-27b³-18ab{3}=27
8a³-27b³-18(2)(3)=27
8a³-27b³-108=27
8a³-27b³=108+27
8a³-27b³=135
agarwalamishsapafplz:
what a wrong answer
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