2a +3b =9 ab =6 find 8a^3+27b^3
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Answer:
8a³+27b³ = -243
Step-by-step explanation:
Given 2a+3b=9 ---(1)
ab = 6 ---(2)
On cubeing both sides of the equation (1) ,we get
(2a+3b)³=9³
=> (2a)³+(3b)³+3×2a×3b(2a+3b)=729
=> 8a³+27b³ +18ab(2a+3b)=729
=> 8a³+27b³+18×6×9=729
=> 8a³+27b³+972=729
=> 8a³+27b³=729-972
=-243
Therefore,
8a³+27b³ = -243
•••♪
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