The function y = ax²: practice problems
The graph of is a parabola with its vertex at the origin, symmetric about the -axis.
Basic, Standard, Advanced: Grade 9 · Term 2
Math problem generator
Equation and graph
Substitute one pair of values into to find . The graph opens upwards if and downwards if ; the larger , the narrower the graph.
Rate of change and ranges
If the domain contains 0, one end of the range is . Do not just evaluate at the endpoints.
Parabolas and lines
If A and B on have -coordinates and , line AB has slope . Split along the -axis to find its area. The line through O and the midpoint of AB halves the area.
Worked examples
For the function , answer the following.
- (1)Find when .
- (2)Find all values of with .
Hint
To find from , rewrite as and take square roots (two answers).
Answer
- (1)
- (2)
Solution
Substitute .
Substitute .
For , the rate of change as goes from to is . Find .
Hint
Express the increase in using and set up the rate of change.
Answer
Solution
The increase in is
Rate of change:
The graph of and a line meet at A and B, whose -coordinates are and . Find the area of , where O is the origin.
Hint
Let C be where AB meets the -axis, and split into and .
Answer
Solution
A, B and line AB:
AB meets the -axis at C. With base OC,
Practice problems
The graph of passes through . Find .
Hint
Substitute the values of and into to find .
Answer
Solution
Substitute into .
For with , find the range of .
Hint
Find at both ends of the domain and sketch the graph to compare.
Answer
Solution
At the ends:
So
The graph of meets line AB at A and B, with -coordinates and . Point P (not O) on the positive -axis makes the area of equal to that of . Find P.
Hint
Let C be where AB meets the -axis. The areas are equal when PC = OC.
Answer
Solution
Line AB:
With C on AB, we need PC = OC.