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If a + b = 1, then the value of a3 + b3 + 3ab is equal to
- A0
- B1
- C2
- D3
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CCommunity
Given that, a + b = 1
Taking cube of both sides, we get
(a + b)3 = 1
⇒ a3 + b3 + 3ab(a + b) = 1
⇒ a3 + b3 + 3ab = 1
Short Trick:
Here, One equation and two variable, so a and b can have infinite value.
let suppose that b = 0
⇒ a = 1
So, a3 + b3 + 3ab
⇒ 13 + 0 + 0 = 1
Taking cube of both sides, we get
(a + b)3 = 1
⇒ a3 + b3 + 3ab(a + b) = 1
⇒ a3 + b3 + 3ab = 1
Short Trick:
Here, One equation and two variable, so a and b can have infinite value.
let suppose that b = 0
⇒ a = 1
So, a3 + b3 + 3ab
⇒ 13 + 0 + 0 = 1