Question:
What is the nature of roots of the quadratic equation $4 x^{2}-12 x-9=0 ?$
Solution:
The given quadric equation is $4 x^{2}-12 x-9=0$
Here, $a=4, b=-12$ and, $c=-9$
As we know that $D=b^{2}-4 a c$
Putting the value of $a=4, b=-12$ and, $c=-9$
$=(-12)^{2}-4 \times 4 \times-9$
$=144+144$
$=288$
Since, $D \geq 0$
Therefore, root of the given equation are real and distinct.