# A problem from polynomials

## Homework Statement

[/B]
Th value of 'a' for which the equation x3+ax+1=0 and x4+ax+1=0 have a common root is?

## The Attempt at a Solution

i initially thought of subtracting both the equations and then finding x and substituting back in the equation but it did not work.

Samy_A
Homework Helper

## Homework Statement

[/B]
Th value of 'a' for which the equation x3+ax+1=0 and x4+ax+1=0 have a common root is?

## The Attempt at a Solution

i initially thought of subtracting both the equations and then finding x and substituting back in the equation but it did not work.
Please show how you did it, and why it did not work.
What you write seems to be the way to go.

Please show how you did it, and why it did not work.
What you write seems to be the way to go.
Please show how you did it, and why it did not work.
What you write seems to be the way to go.
subtracting we get x4-x3=0
x can be 1 or 0.
substituting back in the equation we get a = -2

Samy_A
Homework Helper
subtracting we get x4-x3=0
x can be 1 or 0.
substituting back in the equation we get a = -2
a = -2 : looks correct to me.

a = -2 : looks correct to me.

Samy_A