Question:
The quadratic equation 2x2 – √5x + 1 = 0 has
(a) two distinct real roots
(b) two equal real roots
(c) no real roots
(d) more than 2 real roots
Solution:
(c) Given equation is $2 x^{2}-\sqrt{5} x+1=0$.
On comparing with $a x^{2}+b x+c=0$, we get
$a=2, b=-\sqrt{5}$ and $c=1$
$\therefore$ Discriminant, $\quad D=b^{2}-4 a c=(-\sqrt{5})^{2}-4 \times(2) \times(1)=5-8$
$=-3<0$
Since, discriminant is negative, therefore quadratic equation $2 x^{2}-\sqrt{5} x+1=0$ has no real roots i.e., imaginary roots.