Quadratic graphs, roots and turning points
3 exam-style questions. Answers and the mark for each step are on the last page.
- Question 1
Here is the equation of a curve: .
(a) Work out the value of when .
(b) Which point is the turning point of the curve?
- Question 2
A ball is thrown from ground level. Its height, h metres, after t seconds is for .
(a) Find the two times when the ball is at ground level.
(b) Find the greatest height of the ball.
- Question 3
The curve is a parabola.
(a) Write down the coordinates of the points where the curve crosses the -axis.
(b) Find the coordinates of the turning point of the curve.
(c) For which value of does the equation have exactly one solution?
Answers and marks
Question 1
(a)
- B1 The correct answer, .
(b)
- B1 The correct answer, .
Question 2
(a)
- P1 Set h = 0 and factorise.
- A1 Correct answer:
(b) m
- P1 The greatest height is halfway between the two times, at t = 2.
- A1 Correct answer: m
Question 3
(a) and
- B1 and .
(b)
- P1 Finding the -coordinate, , halfway between the roots.
- P1 Substituting into the equation.
- A1 The correct answer, .
(c)
- B1 The correct answer, .