Thread: polynomial roots

the polynomial x^3 - 4x^2 + 5x - 1 = 0 has 3 roots a,b and y
i. find the value of a + b + y
ii. find the value of aby
iii. find the equation of the polynomial with roots 2a, 2b and 2y


i got 4 for i and 1 for ii
are these right??
how do you do iii.?

Originally Posted by deej813

the polynomial x^3 - 4x^2 + 5x - 1 = 0 has 3 roots a,b and y
i. find the value of a + b + y
ii. find the value of aby
iii. find the equation of the polynomial with roots 2a, 2b and 2y


i got 4 for i and 1 for ii
are these right?? Yes.
how do you do iii.?

If has roots a, b and y then has roots 2a, 2b and 2y.

really?
how do you work that out?
do i simplify to
x^3/8 - 4x^2/4 + 5x/2 -1 = 0 ??

Originally Posted by deej813

really?
how do you work that out?
do i simplify to
x^3/8 - 4x^2/4 + 5x/2 -1 = 0 ??

since if is a root for , then is a root for

oh ok i get it
thanks