← Senior Mathematics Studio

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Choose the labelled shaded region. The four original diagrams are described equivalently by their sides of the boundary lines below.

Read the idea, work independently, then explain what changed.

TOPIC 01

2022 JM01

All three conditions must hold simultaneously.

Try it. Leave your reasoning visible.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Standard#Your turn

Choose the labelled shaded region. The four original diagrams are described equivalently by their sides of the boundary lines below.

y−2x≤4,x+y≥5,y≥2y-2x\le4,\quad x+y\ge5,\quad y\ge2

Official paper · jm01-2022 · I.9 · PDF 3

Official original and suggested answers ↗ · Suggested answer PDF page 5

Skills and prerequisite lessons
  1. I: above y=2 and y=2x+4; below y=5−x
  2. II: above y=2, y=2x+4 and y=5−x
  3. III: above y=2; below y=2x+4 and y=5−x
  4. IV: above y=2 and y=5−x; below y=2x+4
  5. None of these

Working and explanation

BUILD THE REASONING

Hint 1
Isolate y in each inequality.
Hint 2
A boundary is included when equality is allowed.
Worked solution
  1. Convert the system to vertical comparisons.

    y≤2x+4,y≥5−x,y≥2y\le2x+4,\quad y\ge5-x,\quad y\ge2
  2. This is the region above both lower boundaries and below the rising line: IV.

D: region IV.

Checks and common pitfalls: All three conditions must hold simultaneously.

Reasoning checklist · self / teacher assessment
  • Teaching assessment checklist, independently authored. Use the original paper for official marks.
  • Convert the system to vertical comparisons.
    y≤2x+4,y≥5−x,y≥2y\le2x+4,\quad y\ge5-x,\quad y\ge2
  • This is the region above both lower boundaries and below the rising line: IV.

Think first. Reveal a hint when the class is ready.

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Curriculum and source notes ↗