If sum of an infinite geometric series is 4/3 and its Ist term is 3/4, then its common ratio is
7/16
9/16
1/9
7/9
The number of permutations by taking all letters and keeping the vowels of the word COMBINE in the odd places is
96
144
512
576
Sum of the last 30 coefficients in the expansion of (1 + x)59 , when expanded in ascending power of x is
259
258
230
229
If (1 - x + x2)n = a0 + a1x + ... + a2nx2n, then the value of a0 + a2 + a4 + ... + a2n is
D.
Given,(1 - x + x2)n = a0 +a1x +...+ a2nx2n ... (i)
x = 1, then from Eq. (i)
1 = a0 + a1 + ... + a2n ... (ii)
and if x = - 1, then from Eq. (i)
3n = a0 - a1 + a2 - a3 ...+ a2n ...(iii)
Adding Eqs. (ii) and (iii)
1 + 3n = 2[a0 + a2 + a4 + ... + a2n]
Thus, (1 + 3n)/2 = [a0 + a2 + a4 + ... + a2n]