Question

if α,β be the zeroes of the polynomial 2x^2+5x+k such that α^2+β^2+αβ=21/4,thenk=

Answer 1

let (a+b)^2-(a+b)

(-5/2)^2-k/2=21/4

25/4-2k/4=21/4

25-2k=21

k=2