Question

What is the discriminant of the polynomial below?

2x2 + 4x - 9

Answer 1

b2 - 4ac

(whatever that 4's sign is it is positive when squared )

(4)2 - 4(2)(- 9)

16 + 72 = 88

===============Two real roots.

Answer 2

Answer is 88

Explanation:

Given is a quadratic expressions as

`2x^2 + 4x - 9`

We have to find the discriminant.

Compare this to std form of quadratic as

`ax^2 + bx +C`

We have a=2, b =4 and c =-9

ac = -18

b^2 =16

Hence discriminant =

`b^2-4ac \\=16-4(-18)\\=16+72\\=88`