How do you find the discriminant 2x^2+3x-9=0?

Feb 14, 2017

Discriminant is $81$

Explanation:

$2 {x}^{2} + 3 x - 9 = 0$
Comparing with general quadratic equation $a {x}^{2} + b x + c = 0$ we get $a = 2 , b = 3 , c = - 9$
Disciminant is $D = {b}^{2} - 4 a c \mathmr{and} D = {3}^{2} - 4 \cdot 2 \cdot \left(- 9\right) = 9 + 72 = 81$

If $D > 0$ , there is 2 real solution.
If $D = 0$ , there is 1 real solution.
If $D < 0$ , there is no real solution , roots are imaginary.
Discriminant is $81$ [Ans]