Question

What is the discriminant of -2x2 - x-1=0

Answer 1

-7

Explanation:

In the equation of ax² +bx +c= 0, the discriminant (denoted by D) is
`\textcolor{steelblue}{b^(2) - 4ac }`.

-2x² -x -1= 0

Let's identify the values of a, b and c in this equation! It is important to account for the negative sign too.

a= -2, b= -1, c= -1

D

= (-1)² -4(-2)(-1)

= 1 -4(2)

= 1 -8

= -7

Implications of discriminant

• The discriminant tells us the number of roots (solutions) the equation has
• When D < 0, there are no real roots
• When D= 0, there is one real root
• When D > 0, there are two real roots