Answer:
see explanation
Step-by-step explanation:
Given a parabola in standard form
f(x) = ax² + bx + c ( a ≠ 0 )
Then the discriminant Δ = b² - 4ac informs us about the nature of the zeros
• If b² - 4ac > 0 then 2 real and irrational zeros
• If b² - 4ac > 0 and a perfect square then 2 real and rational zeros
• If b² - 4ac = 0 then 2 real and equal zeros
• b² - 4ac < 0 then zeros are not real
Given
f(x) = 3(x - 4)² - 12 ← expand factor using FOIL
= 3(x² - 8x + 16) - 12 ← distribute parenthesis by 3
= 3x² - 24x + 48 - 12
= 3x² - 24x + 36 ← in standard form
with a = 3, b = - 24 , c = 36 , then
b² - 4ac
= (- 24)² - (4 × 3 × 36
= 576 - 432
= 144 ← a perfect square
Then 2 zeros are real and rational and produce 2 x- intercepts
