Question

Which of the following represents the graph of f(x) = 3x2 - 12 ?

Answer 1

f(x) = 3x² - 12

Finding where the graph crosses the axes will help us to determine the correct graph

When x = 0,
f(0) = 3(0)² - 12
f(0) = -12

So we have one point (0, -12)

When y = 0
0 = 3x² - 12
12 = 3x²
4 = x²
√4 = x
x = ⁺/₋ 2

So the graph crosses the x-axis at -2 and 2 and the y-axis at -12

The correct graph is option A