A) 550
B) 625
C) 665
D) 675
Correct Answer: C
Solution :
(c): \[{{\left( 3x-2y \right)}^{3}}={{5}^{3}}\] \[\Rightarrow {{\left( 3x \right)}^{3}}-3\times 3x\times 2y\left( 3x-2y \right)-8{{y}^{3}}=125\] \[\Rightarrow 27{{x}^{3}}-18xy\left( 3x-2y \right)-8{{y}^{3}}=125\] \[=27{{x}^{3}}-18\times 6\times 5-8{{y}^{3}}=125\] \[\Rightarrow 27{{x}^{3}}-8{{y}^{3}}=125+540=665.\]You need to login to perform this action.
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