Question

If the equation `x^2-5x+1=0` has no real roots then 

(a)`k<-2`

(b)`k>2` 

(c) `-2<k<2` 

(d)  None of these 

Answer 1

It is given that the equation `x^2-kx+1=0` has no real roots. 

∴ `(b^2-4ac)<0` 

⇒`(-k)^2-4xx1xx<0` 

⇒` k^2<4` 

⇒`-2<k<2`