We know that while finding the root of a quadratic equation ax2+bx+c=0 by quadratic formula x=−b±√b2−4ac2a,
if b2−4ac>0, then the roots are real and distinct
if b2−4ac=0, then the roots are real and equal and
if b2−4ac<0, then the roots are imaginary.
Here, the given quadratic equation a2−ma+1=0 is in the form ax2+bx+c=0 where a=1,b=−m and c=1.
(i) If the roots are equal then b2−4ac=0, therefore,
b2−4ac=0⇒(−m)2−(4×1×1)=0⇒m2−4=0⇒m2=4⇒m=±√4⇒m=±2
(ii) If the roots are distinct then b2−4ac>0, therefore,
b2−4ac>0⇒(−m)2−(4×1×1)>0⇒m2−4>0⇒m2>4⇒m>±√4⇒m>±2
(iii) If the roots are imaginary then b2−4ac<0, therefore,
b2−4ac<0⇒(−m)2−(4×1×1)<0⇒m2−4<0⇒m2<4⇒m<±√4⇒m<±2
Hence m=±2 if the roots are equal, m>±2 if the roots are distinct and m<±2 if the roots are imaginary.