The number of roots common between the two equations x^3 + 3x^2 + 4x + 5 = 0

The number of roots common between the two equations x3 + 3x2 + 4x + 5 = 0 and x3 + 2x2 + 7x + 3 = 0 is

  1. 0
  2. 1
  3. 2
  4. 3

Answer

Let α is the common root.

α3 + 3α2 + 4α + 5 = 0

α3 + 2α2 + 7α + 3 = 0

Subtracting one equation from another,

α2 - 3α + 2 = 0

α = 2; α = 1

But the above values of α do not satisfy any of the equations. Thus, no root is common.

The correct option is A.