Roots and coefficients of polynomials question (1 Viewer)

[xibu34]

so i thought this was pretty easy and got an answer of -28 for k





so if beta is seven then using the sum of roots and solving we should get -28, but the book says -26 for some reason. can anybody explain please ?

 

[yanujw]

No need to use sums and products of roots.
If -4 is a root then P(-4) = 0
Put x = -4 and you will get k = -26

Additionally, -28 is the constant term. I think you mistook k as being the constant term, when it is actually (k-2), which would show that k= -26