What is a definite integral and how does it relate to the area under a curve?
A definite integral, written as ∫ₐᵇ f(x) dx, represents the exact area under the curve of f(x) from x = a to x = b by taking the limit of Riemann sums as the number of rectangles approaches infinity.
How does increasing the number of rectangles in a Riemann sum affect the approximation of the area under a curve?
Increasing the number of rectangles in a Riemann sum makes the approximation more accurate, and as the number approaches infinity, the sum becomes the exact area, which is the definite integral.
What is the sum and difference rule for definite integrals?
The sum and difference rule states that the integral of a sum or difference of functions equals the sum or difference of their integrals: ∫ₐᵇ [f(x) ± g(x)] dx = ∫ₐᵇ f(x) dx ± ∫ₐᵇ g(x) dx.
What does the constant multiple rule state for definite integrals?
The constant multiple rule states that a constant can be factored out of the integral: ∫ₐᵇ k·f(x) dx = k·∫ₐᵇ f(x) dx.
How does changing the order of the bounds in a definite integral affect its value?
Switching the bounds of integration reverses the sign of the integral: ∫ₐᵇ f(x) dx = -∫ᵦₐ f(x) dx.
What is the value of a definite integral when the upper and lower bounds are the same?
The value is zero: ∫ₐₐ f(x) dx = 0, because there is no interval and thus no area under the curve.
Explain the additivity rule for definite integrals.
The additivity rule states that if c is between a and b, then ∫ₐᶜ f(x) dx + ∫ᶜᵇ f(x) dx = ∫ₐᵇ f(x) dx.
How do you set up a definite integral to find the area under the curve of f(x) from x = 2 to x = 5?
Set up the integral as ∫₂⁵ f(x) dx, which represents the area under f(x) from x = 2 to x = 5.
If you have ∫₀⁴ (x + 1) dx, what does this integral represent?
It represents the exact area under the curve y = x + 1 from x = 0 to x = 4.
Why does integrating from a to a always result in zero area?
Because there is no width between the bounds, so the 'area' under the curve is zero.
What is the main difference between a Riemann sum and a definite integral?
A Riemann sum approximates the area under a curve using a finite number of rectangles, while a definite integral gives the exact area by taking the limit as the number of rectangles approaches infinity.