Unit 5 · 9th Grade Mathematics

Functions &
Transformations.

Transformations of functions — translations, reflections, stretches, and combining function types.

Start studyingTopic B: Multiple Representations & Function Families

Unit 5 — Lesson Video

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Topic A: Transformations of Functions

Lessons 1–5 · Shifts, reflections, and stretches.

01–03 — Lessons 1–3

Vertical & Horizontal Transformations

  • f(x) + k: shift up k. f(x) − k: shift down k.
  • f(x − h): shift right h. f(x + h): shift left h.
  • −f(x): reflect over x-axis. f(−x): reflect over y-axis.
  • af(x), a > 1: vertical stretch. 0 < a < 1: vertical compression.
  • Apply in this order: horizontal shift → reflection → stretch/compression → vertical shift.
g(x) = −2f(x − 3) + 1: shift right 3, reflect over x-axis, stretch by 2, shift up 1.
Practice — Lessons 1–3
Q1 · Multiple Choice

f(x) is shifted 4 units right. The new function is:

Q2 · Multiple Choice

How does g(x) = −f(x) relate to f(x)?

04–05 — Lessons 4–5

Stretches & Compressions

  • Vertical stretch: a·f(x), a > 1 — pulls graph away from x-axis.
  • Vertical compression: a·f(x), 0 < a < 1 — pushes toward x-axis.
  • Horizontal stretch: f(bx), 0 < b < 1.
  • Horizontal compression: f(bx), b > 1.
  • Stretches and compressions change shape, not just position.
g(x) = 3f(x) → every y-value is multiplied by 3 (vertical stretch by factor 3).
Practice — Lessons 4–5
Q3 · Multiple Choice

g(x) = (1/2)f(x). Compared to f(x), g(x) is:

Q4 · Multiple Choice

If f(2) = 6, what is 3f(2)?

Topic B: Multiple Representations & Function Families

Lessons 6–10 · Connecting graphs, tables, equations, and context.

06–10 — Lessons 6–10

Identifying & Comparing Function Families

Match real-world situations and representations to the right function type.

  • Linear: constant rate of change — straight line, y = mx + b.
  • Quadratic: rate of change is changing — parabola, y = ax² + bx + c.
  • Exponential: multiplied by constant factor — rapid growth/decay, y = abˣ.
  • Absolute value: V-shape, y = |x − h| + k.
  • Use tables: if differences are constant → linear. If ratios are constant → exponential.
Table: x=0,1,2,3 → y=1,2,4,8. Each y doubles → exponential: y = 2ˣ.
Practice — Lessons 6–10
Q5 · Multiple Choice

A table shows x: 0,1,2,3 and y: 5,8,11,14. What type of function?

Q6 · Multiple Choice

Which situation is best modeled by an exponential function?