A continuous random variable XXX has a PDF f(x)=k(4x−2x2)f(x) = k(4x - 2x^2)f(x)=k(4x−2x2) for 0≤x≤20 \le x \le 20≤x≤2. Find the value of kkk.
k=12k = \frac{1}{2}k=21
k=38k = \frac{3}{8}k=83
k=23k = \frac{2}{3}k=32
k=14k = \frac{1}{4}k=41