Question
The value of (√2+1)6 + (√2−1)6 will be
Answer: Option B
:
B
(x+a)n + (x−a)n = 2[xn+nC2xn−2a2+nC4xn−4a4+nC6xn−6a6+.......]
Here, n = 6, x =√2, a = 1;
6C2 = 15,6C4 = 15,6C6 = 1
∴ (√2+1)6 + (√2−1)6 = 2[(√2)6+15.(√2)4.1+15(√2)2.1+1.1]
=2[8+15×4+15×2+1]=198
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B
(x+a)n + (x−a)n = 2[xn+nC2xn−2a2+nC4xn−4a4+nC6xn−6a6+.......]
Here, n = 6, x =√2, a = 1;
6C2 = 15,6C4 = 15,6C6 = 1
∴ (√2+1)6 + (√2−1)6 = 2[(√2)6+15.(√2)4.1+15(√2)2.1+1.1]
=2[8+15×4+15×2+1]=198
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