Q.11 If 3a + 2b = 12 and ab = 6 , find the value of 27a ^ 3 + 8b ^ 3 .
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27a³ = 3³×a³ =(3a)³
8b³ =2³×b³ =(2b)³
(x+y)³ = x³+y³+3xy(x+y)
x=3a
x³=27a³
y=2b
y³ = 8b³
3xy = 3×3a×2b = 18ab
(3a+2b)³ = 27a³+8b³ +18ab(3a+2b)
12³ = 27a³+8b³+ 18×6×12
27a³+8b³ =1728- 1296= 432
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