Is it a function? Inputs, outputs, domain and range
Grade 8 Math Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
Rows sorted by input so repeated inputs sit side by side. Bo writes each bus number and the length of its route in miles. Bus 7 passes twice, so it gets written twice. Is it a function, and why?
- No: input 7 appears in two rows
- Yes: no input appears twice, so no bus repeats
- Yes: inputs 2, 7 and 9 each have one output
Read this first
Use the table
input: page output: stickers 4 6 1 3 3 6 2 5 Kira counts the stickers on each page of a sticker book. Page 1 has a shiny dragonfly. Is it a function, and why?
- Yes: inputs 1, 2, 3 and 4 each have one output
- No: inputs 3 and 4 share the output 6
- Yes: no output appears twice, so no count repeats
Pia sorts library books onto shelves. The arrows go from book number to shelf number. Book 6 is huge, so it gets the bottom shelf. Is it a function, and why?
- Yes: inputs 1, 2, 3 and 6 each send one arrow
- No: inputs 1 and 3 both send an arrow to 2
- Yes: no two arrows land on the same output
(2, 7), (4, 1), (6, 3), (2, 5). Ren logs (day, laps run) at the track. On day 2 there were two runs, morning and evening. Is it a function, and why?
- Yes: inputs 2, 4 and 6 each have an output
- No: input 2 has two outputs, 7 and 5
- No: input 4 has two outputs, 1 and 3
(1, 3), (2, 5), (3, 5), (5, 8). Tala weighs a puppy each week and writes (week, pounds). In week 3 the puppy chewed a sock, but only the weight counts. Is it a function, and why?
- Yes: inputs 1, 2, 3 and 5 each have one output
- No: inputs 2 and 3 share the output 5
- Yes: no output appears twice, so no weight repeats
(3, 4), (1, 6), (3, 8), (5, 2). Zee picks carrots and writes (garden row, carrots picked). Row 3 got picked twice, once before lunch and once after. Is it a function, and why?
- No: input 1 has two outputs, 6 and 2
- No: input 3 has two outputs, 4 and 8
- Yes: inputs 1, 3 and 5 each have an output
Ari checks the snow on the porch and plots (hour, inches). The snow took a break between hours 2 and 4. Is it a function, and why?
- No: (2, 5) and (4, 5) are at the same height
- No: the points are not on one straight line
- Yes: inputs 1, 2, 4 and 5 each have one point
Two friends count kites over the park each hour, and Bo plots both counts. At hour 3 they disagree. Is it a function, and why?
- Yes: no two points are at the same height
- No: (3, 2) and (3, 7) are on one up-and-down line
- No: the points do not start at (0, 0)
Use the table
input: minute output: birds 3 5 6 2 3 5 8 4 Milo counts birds at a feeder and writes (minute, birds). Minute 3 got copied twice. What is the domain (all the inputs)? List each value once.
(1, 7), (2, 4), (4, 7), (5, 9). Noah plants sunflower seeds and writes (day, seeds sprouted). What is the range (all the outputs)? List each value once.
