if 4a - 3b = 9 and ab = 2,find the value of 64a^3 - 27b^3
Answers
Answered by
2
Step-by-step explanation:
4a - 3b = 9
ab = 2
now,
64a³ - 27b³
= (4a)³ - (3b)³
=(4a - 3b)³ + 3.4a.3b(4a - 3b)
[a³-b³=(a-b)³+3ab(a-b)]
= (9)³ - 36ab×9
= 729 - 36×2×9
= 729 - 648
= 81
Answered by
3
Answer:
280
Step-by-step explanation:
1st cube of both sides
(4a+3b )³=(10)³
64a³+27b³+3×4a×3b(4a+3b)=1000
64a³+27b³+36ab(4a+3b)=1000
now putting the value of....
64a³+27b³+36ab(4a+3b)=1000
64a³+27b³+720=1000
64a³+27b³=1000-720
64a³+27b³=280
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