Mathematics for IGCSE & O level - Sketching Curves (Section 1 - No. 33)
Which of the following is the graph of a function which does *not* cross the x-axis?
y = x³
y = x² + 1
y = x² - 1
y = 2x + 1
คำอธิบาย
The graph of y = x² + 1 is a parabola that opens upwards, but its vertex is above the x-axis.