Question

Find the discriminant and determine the number of real roots for each equation. Show steps.

-9x^2 + x - 7 = 0

Answer 1

0 real roots

Explanation:

Given a quadratic equation in standard form

ax² + bx + c = 0 ( a ≠ 0 )

Then the discriminant is

Δ = b² - 4ac

• If b² - 4ac > 0 then 2 real and distinct roots

• If b² - 4ac = 0 then 2 real and equal roots

• If b² - 4ac < 0 then the roots are not real

- 9x² + x - 7 = 0 ← is in standard form

with a = - 9, b = 1, c = - 7 , then

b² - 4ac = 1² - (4 × - 9 × - 7) = 1 - 252 = - 251

Since b² - 4ac < 0 then the equation has no real roots