Practice Example 3: Using The Quadratic Formula (4.3) - Quadratic Functions

Practice: Example 3: Using the Quadratic Formula

Lesson 4.3Quadratic Functions

Practise this section

10 questions

Flashcard drill
5 cards from this section. Quick, good the night before a test.
Exercise
6 questions · about 4 min · pass mark 70%. Hints available.
Sign up to start the exercise
Quiz
4 questions · about 3 min · pass mark 70%. Hints available.
Sign up to start the quiz

6 sample questions

Question 1.
State the values of a, b and c in 3x² − 7x + 2 = 0.
Show hintHide hint
Each coefficient keeps the sign written in front of its term.
Question 2.
Find the discriminant of x² + 4x + 4 and say how many real solutions x² + 4x + 4 = 0 has.
Show hintHide hint
Use D = b² − 4ac.
3Question 3.
Which of these is the quadratic formula for ax² + bx + c = 0?
- x = (−b ± √(b² − 4ac)) / (2a)
- x = (b ± √(b² − 4ac)) / (2a)
- x = (−b ± √(b² + 4ac)) / (2a)
Show hintHide hint
Remember the minus in front of b and the minus inside the root.
4Question 4.
What is the discriminant of 2x² − 4x − 6?
- 16
- 32
- 64
- −32
Show hintHide hint
Subtracting a negative product adds it.
Question 5.
The height of a ball, in metres, t seconds after it is thrown is h = −5t² + 20t + 2. Find when the ball hits the ground, to 3 significant figures.
Show hintHide hint
Dividing by 2a = −10 changes the signs, so work carefully.
Question 6.
Show that x² + 2px + p² − 1 = 0 has two real solutions for every value of p, and find them in terms of p.
Show hintHide hint
Expand the discriminant fully; the p² terms cancel.

6 more questions in this section. Enroll free to practise them all.