2a-3b=3 ab=2 find 8a3-27b3
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Hola there,
Given : 2a - 3b = 3 .... equation 1
& ab = 2. .... equation 2
We know that,
(a - b)³ = a³ - b³ - 3ab(a - b)
We will apply this in equation 1, we get;
=> (2a - 3b)³ = 8a³ - 27b³ - 3×6ab(2a - 3b)
=> (2a - 3b)³ = 8a³ - 27b³ - 18ab(3)
=> 8a³ - 27b³ = (2a - 3b)³ - 54ab. ...Ans
Hope this helps...:)
Given : 2a - 3b = 3 .... equation 1
& ab = 2. .... equation 2
We know that,
(a - b)³ = a³ - b³ - 3ab(a - b)
We will apply this in equation 1, we get;
=> (2a - 3b)³ = 8a³ - 27b³ - 3×6ab(2a - 3b)
=> (2a - 3b)³ = 8a³ - 27b³ - 18ab(3)
=> 8a³ - 27b³ = (2a - 3b)³ - 54ab. ...Ans
Hope this helps...:)
jksimons:
27-108=-81
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