Question

Let $x^3+ax+1=0and$ $x^4+a{x}^2+1=0$ have a common root. Then a =

• A. 1
• B. -1
• C. 2
• D. -2

Answer 1

The correct option is D

-2

$x^3+ax+1=0and{x}^4+a{x}^2+1=0$ have a common root. Then ($x^4+a{x}^2+x)-(x^4+a{x}^2+1)=0$

x = 1 is the common root.

1 + a + 1 = 0 a = -2.