Question

show that -k is a root of X^3+(1-k^2)X+k

X^3 means x to be cubed etc..

Answer 1

if -k is a root of that equation, then setting X=-k should result in the equation evaluating to zero

Answer 2

thanks mate but im getting -k^3+k

Answer 3

can you please show your steps so that I can spot where you may have made a mistake?

Answer 4

X^3+(1-K^2)X+k

becomes: (-k)^3+k(1-K^2)+K
-k+k-K^3+k
K^3+k ??

Answer 5

the mistake is in the 1st line after you substituted X=-k