Question

Let f (x) is a 3rd degree polynomial such that f (x2) = 0 has exactly four distinct real roots, then
(A) f (x) = 0 has all three real roots
(B) f (x) = 0 has exactly 2 real roots
(C) f (x) = 0 has only one real root
(D) none of these

Answer 1

f(x^2) has exactly 4 of its 6 roots real and distinct. this means that 2 roots of f(x) are real and non-negative.