8th Grade Understanding Functions Quiz: 10 Questions with Explanations

A \((1, 2), (2, 2), (3, 2)\)B \((0, 1), (1, 3), (2, 5)\)C \((1, 2), (1, 5), (3, 4)\)D \((4, 4), (5, 5), (6, 6)\)

The input 1 has two outputs, 2 and 5.

A \(19\)B \(11\)C \(1\)D \(8\)

3 x 5 – 4 = 11. Adding 4 instead of subtracting gives 19.

A \(y = x + 1\)B \(y = x + 2\)C \(y = 3x\)D \(y = 2x\)

Each output is twice the input.

A \(c = 1.25n\)B \(c = n + 1.25\)C \(c = 1.25 + 2n\)D \(c = \frac{n}{1.25}\)

Each snack costs the same amount, so the cost is the price times the number of snacks. Adding 1.25 to n mixes up the operation.

A LinearB NonlinearC Not a functionD Constant

The graph is a curve, so the rate of change is not constant. It passes the vertical line test, so it is a function.

A \(9\)B \(4\)C \(-4\)D \(-9\)

In y = mx + b, the rate of change is m = -4.

A \(5\)B \(13\)C \(4.33\)D \(41\)

3x – 1 = 14, so x = 5.

A P (rate 4)B R (rate 2)C They are equalD R (it starts higher)

P has rate 4; R changes by 4 for every 2 units of x, a rate of 2. R starts higher, but P rises faster.

A \(y = 6x\)B \(y = x^{2} + 1\)C \(y = 4 – x\)D \(y = 0.5x + 3\)

A squared variable makes the graph a curve.

A it has no slopeB it is too steep to measureC it never touches the y-axisD one input has many outputs

The input of a vertical line, like x = 3, has infinitely many outputs.