Grade 9 Functions — Introduction Practice — Easy

Question 1 of 29Score 0/0Easy

Question 1 of 29: A function assigns exactly ___ output(s) to each input.

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Keep going: Read the lesson: Domain, Range & Function Notation Unit Rate & Ratio Solver Line Grapher (y = mx + b)
Answer key for parents & teachers (29 questions)
  1. A function assigns exactly ___ output(s) to each input.One. By definition, a function assigns exactly one output to each input.
  2. The domain of a function is:The set of all inputs. Domain = all valid inputs (x-values). Range = all outputs (y-values).
  3. The range of a function is:The set of all outputs. Range = set of all possible outputs (y-values) when the domain values are substituted.
  4. If f(x) = 5x + 1, what is f(2)?11. f(2) = 5(2) + 1 = 10 + 1 = 11.
  5. Which test determines if a graph represents a function?Vertical Line Test. Vertical Line Test: if any vertical line crosses the graph more than once, it is NOT a function.
  6. f(x) notation means:f of x (function named f evaluated at x). f(x) reads "f of x" and means: apply the rule f to the input x.
  7. What is the domain of f(x) = √x?x ≥ 0. You can take √0 (= 0) but not √(negative). Domain: x ≥ 0.
  8. What is f(0) for f(x) = 3x² − 2x + 7?7. f(0) = 0 − 0 + 7 = 7. f(0) always gives the constant term.
  9. In y = mx + b, m represents:The slope. In slope-intercept form y = mx + b, m is the slope and b is the y-intercept.
  10. What is the slope of y = 3x − 5?3. In y = 3x − 5, the coefficient of x is 3, so slope = 3.
  11. What is the y-intercept of y = −2x + 7?7. y-intercept is b = 7 (the constant term).
  12. A line with slope 0 is:Horizontal. Slope 0 means no rise over run — the line is perfectly horizontal.
  13. The slope formula is:m = (y₂−y₁)/(x₂−x₁). m = rise/run = Δy/Δx = (y₂−y₁)/(x₂−x₁).
  14. Find the slope of a line through (2, 3) and (6, 7).1. m = (7−3)/(6−2) = 4/4 = 1.
  15. Two lines with the same slope are:Parallel (or identical). Same slope → parallel lines (or the same line if y-intercepts also match).
  16. A linear function grows by a constant ___ per step.Amount (difference). Linear: constant first differences. Each step adds the same amount.
  17. The first differences of a quadratic function are:Increasing linearly. Quadratic: first differences are NOT constant, but second differences are. First differences increase linearly.
  18. Exponential growth multiplies by a constant factor each step. If f(0)=3 and ratio=2, what is f(3)?24. f(3) = 3 × 2³ = 3 × 8 = 24.
  19. Which grows fastest for very large x?Exponential y = 2ˣ. For large x, exponential (2ˣ) eventually outpaces any polynomial, including quadratic.
  20. A table shows: x=0,1,2,3; y=4,12,36,108. What type is this?Exponential. Ratios: 12/4=3, 36/12=3, 108/36=3. Constant ratio = exponential: y = 4 · 3ˣ.
  21. The graph of a quadratic function is:A parabola. Quadratic functions y = ax² + bx + c always graph as parabolas.
  22. Which function has a constant rate of change?y = 5x − 2. Linear functions have constant rate of change (constant slope). y = 5x − 2 has slope 5 everywhere.
  23. In direct variation y = kx, k is called the:Constant of variation. k is the constant of variation (also called constant of proportionality).
  24. In direct variation, as x increases, y:Increases proportionally. Direct variation y = kx (k > 0): as x increases, y increases by the same factor.
  25. If y varies directly with x, which equation fits?y = kx. Direct variation: y = kx (y is directly proportional to x).
  26. If y varies inversely with x, which equation fits?y = k/x. Inverse variation: y = k/x, or equivalently xy = k (constant product).
  27. Find k if y varies directly with x and y = 15 when x = 3.k = 5. k = y/x = 15/3 = 5.
  28. In inverse variation y = k/x, as x doubles, y:Halves. If x → 2x, then y = k/(2x) = (1/2)(k/x). So y halves.
  29. A direct variation graph passes through which special point?The origin (0, 0). y = kx: when x = 0, y = 0. Direct variation always passes through the origin.