Topic Quiz A.7: Functions

Question 1 of 10 · Compare functions in different forms

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Line g appears on the grid below. Function f has the rule f(x) = -x + 4.

Graph of the line y = g(x) on a coordinate plane from -5 to 5 on both axes. The line falls from left to right and passes through the marked points (0, 1) and (2, -3).−5−4−3−2−112345−5−4−3−2−112345xy

Of these two functions, which one decreases faster? Give its rate of change.

Answer choices
Hint

Find g's slope from the two marked points (rise ÷ run). "Decreases faster" means a steeper downhill line.

Question 2 of 10 · Compare proportional relationships

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Laura and Tom are each paid a fixed amount per hour.

  • Laura earned $148.75 for 8.5 hours of work.
  • Tom's pay is shown in the table.
Hours610
Pay ($)99.00165.00

How much more does the higher-paid person earn in a 40-hour week?

$

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Find each hourly rate (pay ÷ hours). Then decide who earns more and use 40 hours.

Question 3 of 10 · Compare proportional relationships

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A store manager wants every price rule to match $0.75 per item, with no extra fees. Which of these relationships are proportional and have a constant of proportionality k = 0.75? Select all that apply.

Select all that apply.

Answer choices
Hint

For each one, check two things: does it go through (0, 0), and is \frac{y}{x} always 0.75?

Question 4 of 10 · Compare proportional relationships

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The graph shows the cost of ribbon at a craft store.

Line graph of the cost of ribbon. Horizontal axis: ribbon in yards, 0 to 10. Vertical axis: cost in dollars, 0 to 12 in steps of 2. A straight line starts at (0, 0) and passes through the marked points (5, 6) and (10, 12).012345678910024681012Ribbon (yards)Cost (dollars)(5, 6)(10, 12)

Which statement correctly describes the unit rate shown by the graph?

Answer choices
Hint

The unit rate is the cost of exactly 1 yard. Where is the line when x = 1?

Question 5 of 10 · Identify functions

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Four graphs on coordinate planes from -4 to 4. Graph A: a parabola opening to the right, x = y squared minus 3, with vertex at (-3, 0). Graph B: a straight line falling from left to right through (0, 1) and (2, -3). Graph C: a vertical line x = 2. Graph D: an S-shaped cubic curve that always rises from left to right and passes through (0, 0).−4−3−2−11234−4−3−2−11234xyGraph A−4−3−2−11234−4−3−2−11234xyGraph B−4−3−2−11234−4−3−2−11234xyGraph C−4−3−2−11234−4−3−2−11234xyGraph D

Select all graphs that represent y as a function of x.

Select all that apply.

Answer choices
Hint

Use the vertical line test on each graph. Be careful with lines: which direction fails?

Question 6 of 10 · Evaluate linear and quadratic functions

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Let k(x) = x^2 - 4.

Click the point on the coordinate plane that represents \big(-1,\ k(-1)\big).

Click on the figure to mark your answer (or focus it and use the arrow keys).

Coordinate plane from -5 to 5 on both axes-5-5-4-4-3-3-2-2-1-11122334455xy
Hint

First find k(-1). Remember that (-1)^2 is positive. Then plot (input, output).

Question 7 of 10 · Evaluate linear and quadratic functions

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For the function g(x) = -5x + 8, exactly one input produces an output of 33. Find that input.

x =

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Here 33 is the output. Set -5x + 8 equal to 33 and solve. Watch the sign when you divide.

Question 8 of 10 · Identify functions

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A shuttle bus drives a loop and visits some stops twice. Its morning schedule is shown.

Stop number123431
Arrival time7:057:127:207:317:407:52
  • Relation I: input = stop number, output = arrival time.
  • Relation II: input = arrival time, output = stop number.

Which statement is true?

Answer choices
Hint

Check each relation separately. Which column is the input in each one, and does any input repeat?

Question 9 of 10 · Compare functions in different forms

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The function f is defined by f(x) = -x^2 + 10. The function g is a line with slope 2 that passes through the point (1, 3).

Complete the statements.

f(3) =

g(3) =

At x = 3, f is g.

Choose an answer from each menu.

Hint

For f, square first, then apply the negative sign. For g, start at (1, 3) and move 2 units right, rising 2 for each unit.

Question 10 of 10 · Identify functions

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A relation is shown in the table, where a is an unknown number.

xa369
y104102

Which value of a would make the relation NOT a function?

Answer choices
Hint

Try each choice. Does the new pair (a, 10) clash with another column that has the same input but a different output?

Formula sheet

Area

Area of a square s = length of a side
A = s^2
Area of a rectangle l = length, w = width
A = lw
Area of a parallelogram b = base, h = height (straight up from the base, not the slanted side)
A = bh
Area of a triangle b = base, h = height
A = \tfrac{1}{2}bh
Area of a trapezoid b_1 and b_2 = the two parallel sides, h = height
A = \tfrac{1}{2}h(b_1 + b_2)
Area of a circle r = radius (half of the diameter); \pi \approx 3.14
A = \pi r^2

Perimeter and circumference

Perimeter of a square s = length of a side
P = 4s
Perimeter of a rectangle l = length, w = width
P = 2l + 2w
Perimeter of a triangle s_1, s_2, s_3 = the three side lengths
P = s_1 + s_2 + s_3
Circumference of a circle the distance around a circle; r = radius, d = diameter, \pi \approx 3.14
C = 2\pi r = \pi d

Surface area (SA) and volume (V)

p = perimeter of the base with area B; \pi \approx 3.14

Rectangular prism l = length, w = width, h = height
SA = 2lw + 2lh + 2wh \qquad V = lwh
Right prism B = area of the base, p = perimeter of the base, h = height
SA = ph + 2B \qquad V = Bh
Cylinder r = radius of the base, h = height
SA = 2\pi rh + 2\pi r^2 \qquad V = \pi r^2 h
Pyramid B = area of the base, p = perimeter of the base, s = slant height, h = height
SA = \tfrac{1}{2}ps + B \qquad V = \tfrac{1}{3}Bh
Cone r = radius of the base, s = slant height, h = height
SA = \pi rs + \pi r^2 \qquad V = \tfrac{1}{3}\pi r^2 h
Sphere r = radius
SA = 4\pi r^2 \qquad V = \tfrac{4}{3}\pi r^3

Data

Mean (average) add all the values of the data set, then divide by how many values there are
\text{mean} = \dfrac{\text{total of the values}}{\text{number of values}}
Median
the middle value when the data are in order; with an even number of values, it is the mean of the two middle values

Algebra

Slope of a line (x_1, y_1) and (x_2, y_2) = two points on the line
m = \dfrac{y_2 - y_1}{x_2 - x_1}
Slope-intercept form of a line m = slope, b = y-intercept (where the line crosses the y-axis)
y = mx + b
Point-slope form of a line m = slope, (x_1, y_1) = a point on the line
y - y_1 = m(x - x_1)
Standard form of a quadratic equation a, b, c are numbers and a \ne 0
y = ax^2 + bx + c
Quadratic formula solves ax^2 + bx + c = 0
x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}
Pythagorean theorem in a right triangle: a, b = the two legs, c = the hypotenuse (the longest side, across from the right angle)
a^2 + b^2 = c^2
Simple interest I = interest, P = principal (the amount saved or borrowed), r = rate per year as a decimal, t = time in years
I = Prt
Distance = rate × time d = distance, r = rate (speed), t = time
d = rt
Total cost
\text{total cost} = (\text{number of units}) \times (\text{price per unit})