The number of positive integers x , for which the function f(x)=(2x−1)x2−10x−11 is not defined is

(2x−1)(x2−10x−11)≥0                 (2x−1)(x+1)(x−11)≥0                 f  is not defined at (x≠−1,  11)                 x∈(−∞,−1)∪(12,11)                 Number of +ve integer = 11