TheIB Exam Practice · Paper 1 Step by Step (SL): completing the square · part 01
Complete the Square in 7 Minutes (9-Mark Paper 1 Breakdown)
A nine mark Paper 1 style question on quadratics, solved line by line with no calculator: complete the square, read the vertex and the axis of symmetry, and use the word “hence” to solve the equation. For IB Mathematics: Analysis and Approaches SL (HL students need it too).
In this lesson
- 0:00 The question
- 0:17 Read it like an examiner
- 1:04 Part (a): complete the square
- 2:22 Part (b): vertex and axis of symmetry
- 3:08 Part (c): hence solve
- 3:45 Check with a sketch
- 4:34 What earns the marks
- 5:15 Your turn
- 5:54 Recap
- 6:14 Next Saturday
Answers to the practice questions at the end of the video
- q(x) = (x − 4)² − 9 [2]; vertex (4, −9) [1]; x − 4 = ±3, so x = 1 or x = 7 [2].
- p(x) = 3(x + 2)² − 7 [3]; the minimum value is −7, so there are no solutions when k is less than −7 [2].
Questions are original, in the style of the exam; marks are estimates.
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