Question

Question #1cabf

Answer 1

a) `k^2-16k+60`
b) `k=6, 10`
c) as in explanation

Explanation:

a) in `ax^2+bx+c=0 (b^2-4ac)=>(-k-8)^2-4*1*(8k+1)=k^2-16k+60`
`b) b^2-4ac=0`=>two equal roots=>`k^2-16k+60=0=>(k-6)(k-10)=0=>`k=6 or k=10
c) when `b^2-4ac<0, f(x)` is always more than 0
so if `k=8, b^2-4ac=-4<0`, and `f(x)>0` always (when `a>0)`