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Question
Expand.
`(2m + 1/5)^3`
Sum
Solution
Here, a = 2m, b = `1/5`
We know that,
(a + b)3 = a3 + 3a2b + 3ab2 + b3
∴ `(2m + 1/5)^3 = (2m)^3 + 3(2m)^2(1/5) + 3(2m)(1/5)^2 + (1/5)^3`
= `2^3m^3 + 3/5(2^2 m^2) + 6m xx 1^2/5^2 + 1^3/5^3`
= `8m^3 + 12/5 m^2 + (6m)/25 + 1/125`
∴ `(2m + 1/5)^3 = 8m^3 + 12/5 m^2 + 6/25m + 1/125`
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