Write A Function Describing A Relationship
Overview
Real problems rarely arrive as equations. They arrive as descriptions: a taxi charges a fixed fee plus a rate per mile, a tank drains at a steady rate, a savings balance grows each year. Turning such a description into a function is one of the most useful skills in all of algebra, because once you have the function you can answer any question about the situation.
In this lesson you will write a function that describes the relationship between two quantities. You will identify the input and the output, capture any fixed amount and any rate of change, and assemble them into a clear rule in function notation.
Objectives
- Write a function that describes a relationship between two quantities.
Audio Lesson
Listen to this lesson in the app
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Write A Function Describing A Relationship. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- A taxi charges $3 plus $2 per mile. Which function gives the cost C for m miles? A. C(m) = 3m + 2 B. C(m) = 2m + 3 C. C(m) = 5m D. C(m) = 6m Answer: B
- Using C(m) = 2m + 3, what is the cost of a 5-mile journey? A. $10 B. $13 C. $16 D. $25 Answer: B
- A rectangle has fixed width 4 and length x. Its area function is: A. A(x) = x + 4 B. A(x) = 4x C. A(x) = 4 + x D. A(x) = x/4 Answer: B
- In a linear model f(x) = (rate)x + (fixed value), the fixed value is the: A. coefficient of x B. constant term C. input D. output Answer: B
- Which question helps you find the rate of change? A. What stays the same? B. How much does the output change per unit of input? C. What is the largest value? D. What is the input called? Answer: B
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on Write A Function Describing A Relationship? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
