Question

whats the answer of this question​

Answer 1

since all roots are given to be positive

applying AM=GM

let the roots be x

then

x^4=5 (using theory of equation)

p=x+x+x+x=4x

r=x.x.x+x.x.x+x.x.x+x.x.x=4x^3

pr=4x.4x^3=16x^4=16*5=80