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Ch-8: Application of Integrals
12 Questions
Before You Practice Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
1. The area between a curve y = f(x) and the x-axis from x = a to x = b is generally given by:
A. ∫[a to b] f(x) dx (taking the absolute value where the curve dips below the axis)
B. f(b) - f(a)
C. f'(b) - f'(a)
D. Just the value f(a)
Show Answer
Answer: A. ∫[a to b] f(x) dx (taking the absolute value where the curve dips below the axis)
Explanation: Definite integration gives signed area, so portions below the x-axis must be taken as positive when computing actual area.
2. The area enclosed between two curves y = f(x) and y = g(x) is found by integrating:
A. [f(x) - g(x)] over the appropriate interval
B. The product f(x) · g(x)
C. The sum f(x) + g(x)
D. Only f(x)
Show Answer
Answer: A. [f(x) - g(x)] over the appropriate interval
Explanation: The area between two curves is the integral of the difference between the upper and lower functions over their common interval.
3. To find area using integration, we typically consider:
A. Vertical or horizontal elementary strips
B. Only triangles
C. Isolated points
D. Only circular arcs
Show Answer
Answer: A. Vertical or horizontal elementary strips
Explanation: The area is approximated as a sum of thin rectangular strips, whose width tends to zero in the limiting integral.
4. The area of a circle x² + y² = r² can be determined using:
A. Integration techniques with appropriate limits
B. Differentiation alone
C. Matrices
D. Simple algebra without calculus
Show Answer
Answer: A. Integration techniques with appropriate limits
Explanation: By integrating the equation of the upper semicircle over the correct limits (and doubling), the standard area formula πr² can be derived.
5. When a portion of a curve lies below the x-axis, the corresponding definite integral gives:
A. A negative value, so its absolute value must be taken for area
B. Always a positive value directly
C. Always zero
D. An undefined result
Show Answer
Answer: A. A negative value, so its absolute value must be taken for area
Explanation: Since area below the x-axis contributes negatively to the signed integral, its magnitude must be used to represent actual geometric area.
6. The area bounded by a curve and the y-axis is obtained by integrating with respect to:
A. y
B. x
C. Both x and y simultaneously
D. Neither variable
Show Answer
Answer: A. y
Explanation: When the boundary of interest is the y-axis, it is more convenient to express x as a function of y and integrate with respect to y.
7. When finding the area between two intersecting curves, the first step is generally to find:
A. The points of intersection by solving the equations simultaneously
B. The derivative of both curves
C. The slopes of the curves
D. The matrix of coefficients
Show Answer
Answer: A. The points of intersection by solving the equations simultaneously
Explanation: The points of intersection determine the limits of integration for the enclosed region.
8. The area under a curve, as studied in this chapter, is a direct application of the:
A. Definite integral
B. Indefinite integral
C. Derivative
D. Limit of a sequence
Show Answer
Answer: A. Definite integral
Explanation: Definite integrals provide the numerical value of the area bounded between a curve and the axis over a specific interval.
9. If a region is bounded by a curve and both coordinate axes, its area is computed by:
A. Integrating over the appropriate sub-intervals
B. Using differentiation only
C. Using matrices
D. Using determinants
Show Answer
Answer: A. Integrating over the appropriate sub-intervals
Explanation: The region is often split into parts based on where the curve intersects the axes, and each part is integrated separately.
10. The area of the region bounded by an ellipse can be computed using:
A. Integration involving the ellipse's equation
B. Simple geometry formulas alone
C. Matrices
D. Vector algebra
Show Answer
Answer: A. Integration involving the ellipse's equation
Explanation: Similar to a circle, the area enclosed by an ellipse can be derived by integrating its equation over the appropriate limits.
11. To compute area using horizontal strips, integration is carried out with respect to:
A. y
B. x
C. Time
D. Neither variable
Show Answer
Answer: A. y
Explanation: Horizontal strips have their width as a function of y, so the area is obtained by integrating with respect to y.
12. The application of integrals, as studied in this chapter, is primarily used to determine:
A. Areas of regions bounded by curves
B. Slopes of tangent lines
C. Only instantaneous rates of change
D. Limits of sequences
Show Answer
Answer: A. Areas of regions bounded by curves
Explanation: This chapter focuses on using definite integrals to calculate areas enclosed by curves, lines, and combinations of both.