Question

Find the value of the discriminant (D) and describe the roots for the quadratic equation shown below.

y= ax + bx + c
y= x + 3x-4

A. D= -7 and the roots are irrational.
B. D = 22 and the roots are irrational.
C. D= 25 and the roots are rational.
D. D=5 and the roots are rational.​

Answer 1

Answer: C

Explanation:

y = ax + bx + c is the general equation for quadratic function. While the discriminant D is

D = b^2 - 4ac

You are given the equation:

y = x^2 + 3x - 4

Where a = 1, b = 3 and c = -4

Substitutes all the parameters into the discriminant D formula

D = 3^2 - 4 × 1 × -4

D = 9 - ( - 16 )

Open the bracket

D = 9 + 16

D = 25

Therefore, D = 25 and the roots are rational