Grade 12 Derivatives Practice — Easy

Question 1 of 30Score 0/0Easy

Question 1 of 30: The derivative f'(x) is defined as:

More Grade 12 practice

Keep going: Read the lesson: Definition of the Derivative Derivative Solver
Answer key for parents & teachers (30 questions)
  1. The derivative f'(x) is defined as:lim_{h→0} [f(x+h)−f(x)]/h. The derivative is the limit of the difference quotient as h → 0: f'(x) = lim_{h→0}[f(x+h)−f(x)]/h.
  2. Geometrically, f'(a) represents:The slope of the tangent line to f at x=a. The derivative at a point equals the slope of the tangent line at that point.
  3. The difference quotient [f(x+h)−f(x)]/h represents:The average rate of change over interval h. The difference quotient is the average rate of change over a small interval h. As h→0, it becomes the instantaneous rate.
  4. Using the definition, f'(x) for f(x) = x²:2x. lim_{h→0}[(x+h)²−x²]/h = lim[(2xh+h²)/h] = lim[2x+h] = 2x.
  5. Using the limit definition, the derivative of f(x) = c (constant) is:0. f'(x) = lim[c−c]/h = lim[0/h] = 0. The derivative of a constant is always zero.
  6. The derivative of f(x) = 5x using the limit definition:5. lim[(5(x+h)−5x)/h] = lim[5h/h] = lim[5] = 5.
  7. The derivative of f(x) = x³ (using definition or power rule) is:3x². d/dx[x³] = 3x². (Or verify via limit: lim[(x+h)³−x³]/h = lim[3x²+3xh+h²] = 3x².)
  8. The notation f'(x), dy/dx, and Df(x) all mean:The derivative of f with respect to x. These are three equivalent notations for the derivative: Lagrange notation f'(x), Leibniz notation dy/dx, and operator notation Df(x).
  9. Using the limit definition, find f'(2) for f(x) = x²:4. f'(x) = 2x. f'(2) = 2(2) = 4.
  10. The slope of the tangent line to y = x² at x = 3 is:6. dy/dx = 2x. At x = 3: slope = 2(3) = 6.
  11. The second derivative f''(x) is:The derivative of the derivative (f'). The second derivative is f''(x) = d/dx[f'(x)] — the derivative of the first derivative.
  12. If f'(x) > 0 on an interval, then f is:Increasing. Positive derivative means the function is increasing (slope is positive).
  13. The power rule: d/dx[xⁿ] = ?nxⁿ⁻¹. d/dx[xⁿ] = nxⁿ⁻¹. Multiply by the exponent and reduce the power by 1.
  14. d/dx[x⁵] = ?5x⁴. d/dx[x⁵] = 5x⁴. Power rule: bring down 5, reduce power to 4.
  15. d/dx[eˣ] = ?. The exponential function eˣ is its own derivative: d/dx[eˣ] = eˣ.
  16. d/dx[ln x] = ?1/x. d/dx[ln x] = 1/x. This is one of the most important derivative formulas.
  17. d/dx[sin x] = ?cos x. d/dx[sin x] = cos x.
  18. d/dx[cos x] = ?−sin x. d/dx[cos x] = −sin x. Note the negative sign.
  19. Product rule: d/dx[f·g] = ?f'g + fg'. Product rule: d/dx[fg] = f'g + fg'. Differentiate first, keep second; keep first, differentiate second.
  20. In implicit differentiation, we differentiate both sides with respect to:x. We differentiate both sides with respect to x. When a y-term appears, the chain rule introduces dy/dx.
  21. When differentiating y² implicitly with respect to x:2y·(dy/dx). d/dx[y²] = 2y·(dy/dx). Chain rule: y is a function of x, so we multiply by its derivative dy/dx.
  22. For x² + y² = 25, dy/dx = ?−x/y. 2x + 2y(dy/dx) = 0 → dy/dx = −x/y.
  23. In related rates, we differentiate all variables with respect to:Time t. Related rates problems involve quantities that all change with time. We differentiate with respect to t.
  24. Which strategy is FIRST in solving related rates problems?Draw a diagram. First draw a diagram and label variables. Then write a relating equation, THEN differentiate, THEN substitute.
  25. A 10-foot ladder slides. x is the base from wall, y is the top height. The constraint is:x² + y² = 100. Pythagorean theorem: x² + y² = 10² = 100.
  26. The key to related rates is recognizing which quantities are:Changing with time. Related rates problems involve quantities that all change with time (or another variable). Identifying which quantities vary is the first conceptual step.
  27. A critical point of f occurs where:f'(x) = 0 or f'(x) is undefined. Critical points occur where f'(x) = 0 or where f'(x) doesn't exist. These are candidates for local extrema.
  28. If f'(x) > 0 on (a,b), then f is:Increasing on (a,b). Positive first derivative ↔ increasing function.
  29. If f'(x) < 0 on (a,b), then f is:Decreasing on (a,b). Negative first derivative ↔ decreasing function.
  30. The tangent line to y = f(x) at point (a, f(a)) is:y − f(a) = f'(a)(x − a). Tangent line equation: y − f(a) = f'(a)(x − a). Uses point-slope form with derivative as slope.