+
-
²
÷
×

Grade 8 Functions & Relationships Quiz

Inputs, Outputs, Flow Diagrams, Tables and Formulae

What this quiz covers

grade8_functions_quiz1 draws its questions at random from a bank of 13 questions, with full worked solutions for every one.


Worked examples

A few of the question types, with full solutions, so you know what to expect.

In the relationship \(x \rightarrow \text{rule} \rightarrow y\), what is \(x\) called?

  1. The input
  2. The output
  3. The rule
  4. The answer

Answer: The input

\(\text{The input is the number you start with.}\)

\(\text{The rule turns the input into the output.}\)

The rule is "add 5". What is the output for input \(x=-2\)?

  1. 3
  2. \(-7\)
  3. 7
  4. \(-3\)

Answer: 3

\(y=x+5\)

\(y=-2+5=3\)

Use the flow diagram \(x \rightarrow \times 3 \rightarrow +1 \rightarrow y\). What is \(y\) when \(x=4\)?

  1. 13
  2. 12
  3. 15
  4. 16

Answer: 13

\(\text{First multiply by 3: } 4\times3=12\)

\(\text{Then add 1: } 12+1=13\)

Which formula matches the flow diagram \(x \rightarrow \times 6 \rightarrow -4 \rightarrow y\)?

  1. \(y=6x-4\)
  2. \(y=6(x-4)\)
  3. \(y=-4x+6\)
  4. \(y=x-4\times6\)

Answer: \(y=6x-4\)

\(\text{Read the operations in order: multiply by 6, then subtract 4.}\)

A table shows \(x\): 1, 2, 3, 4 and \(y\): 5, 8, 11, 14. What is the rule?

  1. \(y=3x+2\)
  2. \(y=3x-2\)
  3. \(y=5x\)
  4. \(y=x+4\)

Answer: \(y=3x+2\)

\(\text{Outputs increase by 3, so start with } 3x\)

\(\text{Test } x=1\text{: } 3(1)=3\text{, but the output is 5, so add 2.}\)

\(\text{Check: } 3(4)+2=14\)