Answer + Step-by-step explanation:
Consider the equation :
5x² - 20x + k = 0
∆ = b² − 4bc is the discriminant of the quadratic equation.
In our equation :
a = 5 ; b= -20 ; c = k
Then
∆ = (-20)² − 4×5×k
= 20² − 20k
= 20×(20 − k) (Factoring)
The equation 5x² - 20x + k = 0 has exactly one real solution
if and only if ∆ = 0.
Solving the equation ∆ = 0 :
∆ = 0
⇔ 20×(20 − k) = 0
⇔ (20 − k) = 0 (Zero product property)
⇔ k = 20
