The number of positive zeros of the polynomial ∑ j ∈ [0,n] ^nCr(-1)^r x^r is ___ (a) 0 (b) n (c) < n (d) r

Question

The number of positive zeros of the polynomial \(\displaystyle\sum_{j=0}^{n} \) ⁿC_r(-1)^r x^r is ___

(a) 0 

(b) n 

(c) < n

(d) r

Answer 1

(b) The answer is n.