Question

$A{x}^3+B{x}^2+Cx+D=0$ Two roots are equal in magnitude and opposite in sign. If there are two negative roots which of the following is correct.

• A. B/A is always positive
• B. C/A always positive
• C. D/A is always positive
• D. B/C is always positive

Answer 1

The correct option is A

B/A is always positive

Given question is variable to variable question.

Let three roots of cubic equation be -2, -1 and 1. Then cubic equation is (x + 2)(x + 1)(x - 1) = 0

Where A = 1, B = 2, C = - 1 and D = - 2.
Only option (a) will satisfy given the condition.