Algebra 8

3 marks · Normal

Let the function f be defined by f(x) = 3x - 5 with domain {2, 4, 5, 7}.

Find the range of f.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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{1, 7, 10, 16}

Also accept: Range = {1, 7, 10, 16}; {1; 7; 10; 16}; 1, 7, 10, 16 (clearly listed)

Common mistakes: Listing values not in the range.; Not using the correct domain values.

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Substitutes each domain value into f(x).

A1 · 1 mark · Finds at least two correct range values.

A2 · 1 mark · States complete, correct range as a set of four values in any order.

Worked solution

For x = 2: f(2) = 3×2 - 5 = 6 - 5 = 1

For x = 4: f(4) = 3×4 - 5 = 12 - 5 = 7

For x = 5: f(5) = 3×5 - 5 = 15 - 5 = 10

For x = 7: f(7) = 3×7 - 5 = 21 - 5 = 16

Range = {1, 7, 10, 16}