It is known that (r + 1)th term, (Tr+1), in the binomial expansion of (a + b)n is given by
Assuming that x2 occurs in the (r + 1)th term of the expansion (1 +x)m, we obtain
Comparing the indices of x in x2 and in Tr + 1, we obtain r = 2
Therefore, the coefficient of x2 is mC2
It is given that the coefficient of x2 in the expansion (1 + x)m is 6.
Thus, the positive value of m , for which the coefficient of x2 in the expansion (1 + x ) m is 6, is 4.
