Question

If 27a + 9b + 3c + d = 0, then the equation

4ax³ + 3bx² + 2cx + d = 0 has at least one real root lying between-

• A. 0 and 1
• B. 1 and 3
• C. 0 and 3
• D. 0 and 2

Answer 1

Answer: (C)

0 and 3

Answer 2

Let f(x) = ax⁴ + bx³ + cx² + dx;

as f(0) = 0 and f(3) = 0 ; (given)

so by Rolle's theorem