Question

What is the discriminant in the quadratic equation x2 + 11x + 121 = x + 96?
     A. 0 B. 100 C. 20 D. 200

Answer 1

Given:
x² + 11x + 121 = x + 96

First, we need to convert it into a quadratic equation.

x² + 11x - x + 121 - 96 = 0
x² + 10x + 25 = 0

a = 1 ; b = 10 ; c = 25

Quadratic formula:

x = (-b + (√b² - 4ac)) ÷ 2a

The discriminant is under the radical sign

discriminant ⇒ b² - 4ac ⇒ 10² - 4(1)(25) ⇒ 100 - 100 = 0

Correct answer is A. 0

Answer 2

x² + 11x + 121 = x + 96

x² + 11x - x + 121 - 96 = 0

x² + 10x + 25 = 0.  Compare to ax² + bx + c = 0.

a = 1, b = 10, c = 25.

Discriminant, Δ = (b² - 4ac)

=  (10² - 4*1*25)

= (100 - 100)

= 0.

Discriminant = 0

Option A.