- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals3h 25m
5. Graphical Applications of Derivatives
Applied Optimization
Problem 4.5.23
Textbook Question
Closest point on a curve What point on the parabola y = 1 - x² is closest to the point (1, 1)?

1
To find the point on the parabola y = 1 - x^2 that is closest to the point (1, 1), we need to minimize the distance between a point (x, y) on the parabola and the point (1, 1). The distance D between these two points is given by the formula D = \sqrt{(x - 1)^2 + (y - 1)^2}.
Since y = 1 - x^2 for points on the parabola, substitute y in the distance formula to get D = \sqrt{(x - 1)^2 + ((1 - x^2) - 1)^2}. Simplify the expression inside the square root to get D = \sqrt{(x - 1)^2 + (-x^2)^2}.
To simplify the problem, minimize the square of the distance instead of the distance itself, as the square root function is monotonically increasing. Define the function f(x) = (x - 1)^2 + (-x^2)^2 and find its minimum value.
Differentiate f(x) with respect to x to find the critical points. The derivative f'(x) = 2(x - 1) + 2(-2x)(-x^2) = 2(x - 1) + 4x^3. Set f'(x) = 0 to find the critical points.
Solve the equation 2(x - 1) + 4x^3 = 0 for x. This will give you the x-coordinate of the point on the parabola that is closest to (1, 1). Substitute this x value back into y = 1 - x^2 to find the corresponding y-coordinate.
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