Question
Question: If (1+ x + 2 x<sup>2</sup>)<sup>20</sup> = a<sub>0</sub> + a<sub>1</sub>x + a<sub>2</sub>x<sup>2</su...
If (1+ x + 2 x2)20 = a0 + a1x + a2x2 + ....... + a40 x40 fud a1 + a3 + a5 + ........ + a37 + a39 =
A
2420
B
2420–220
C
2220
D
None of these
Answer
2420–220
Explanation
Solution
Put x = 1, x = – 1 and subtract then
(4)20 – 220
= 2[a1 + a3 + ......+a39]