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一変数の微積分

微分

01微分係数とは何か：接線の傾きとして定義する 02割線から接線へ：極限による微分係数の定義 031/x の導関数：先に約分、極限はそのあと 041/x の接線と、面積がいつも2になる三角形 05微分の記法とべき関数の微分公式問題セット0/10 問題セット20/10 MIT 問題セット0/3

01瞬間の変化率としての導関数 ― 平均の速さの二倍 02時間のない変化率：気温の勾配と GPS の感度 03代入で求まる極限、0/0、片側極限 04連続性とは二つの数の比較：跳躍不連続点と除去可能な不連続点 05無限大に発散する不連続点：1/x とその導関数 06微分可能なら連続：一行で終わる証明と、0 でわらない理由問題セット0/10 問題セット20/10

01Two Kinds of Formula, and the Derivative of Sine 02The Derivative of Cosine, and Two Limits at Zero 03Bow and Bowstring: Proving the Two Trig Limits 04Why the Trig Derivatives Hold Only in Radians 05A Geometric Proof: Sine as a Height on the Circle 06Finishing the Proof, and the Product and Quotient Rules 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01Proving the Product Rule: Change One Factor at a Time 02The Quotient Rule, and the Power Rule for Negative Exponents 03The Chain Rule: Differentiating a Function of a Function 04Higher Derivatives: The Sine Cycle and Three Notations 05The nth Derivative of xⁿ Is n Factorial, by Induction 問題セット0/10 問題セット20/10 MIT 問題セット0/2

01The Power Rule for Rational Exponents 02The Slope of a Circle, Two Ways 03Implicit Differentiation of a Quartic Curve 04Inverse Functions and the Reflection Across y = x 05Derivatives of the Arctangent and Arcsine 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01The Derivative of aˣ and the Mystery Number M(a)02Defining e by Slope One, and the Derivative of ln x 03M(a) = ln a: Differentiating aˣ and xˣ 04Why (1 + 1/n)ⁿ Approaches e 問題セット0/10 問題セット20/10 MIT 問題セット0/1

微分の応用

01Linear Approximation: A Curve Is Its Tangent Line 02Five Linear Approximations at Zero 03Combining Approximations, from Algebra to GPS Clocks 04Quadratic Approximation: The Best-Fit Parabola 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01Linear Approximation as a Proportionality Rule 02Quadratic Approximation: Why the ½, and Products 03Curve Sketching: The Sign of f′ and Critical Points 04Curve Sketching: Ends, Concavity and Inflection 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01Sketching Without Critical Points: (x+1)/(x+2)02A Five-Step Curve-Sketching Scheme, Applied to x / ln x 03x / ln x: Inflection Point and Where Max and Min Can Occur 問題セット0/10 問題セット20/10

01Two Squares From One Wire: The Critical Point Gives the Least Area 02The Open Box of Fixed Volume: Least Material When x = 2y 03Related Rates: The Police Radar and the Conical Tank 問題セット0/10 問題セット20/10 MIT 問題セット0/4

01The Hanging Ring: Why the String Makes Equal Angles 02Newton's Method: Tangent Lines That Find the Square Root of Five 03Why Newton's Method Doubles Its Digits, and How It Fails 04The Mean Value Theorem: Somewhere You Hit Your Average Speed 05Positive Derivative Means Increasing: Proving eˣ Exceeds 1 + x 問題セット0/10 問題セット20/10 MIT 問題セット0/2

積分

01Differentials: dy = f′(x) dx and the Cube Root of 64.1 02Antiderivatives Differ Only by a Constant 03Integration by Substitution and Advanced Guessing 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01Separation of Variables: dy/dx = −xy and the Bell Curve 02General Solutions: Signs, Constants and Initial Conditions 03Orthogonal Trajectories: Parabolas and Crossing Ellipses 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01The Definite Integral: Area as a Limit of Rectangle Sums 02Area Under y = x²: Squeezing the Sum of Squares 03Sigma Notation and the Area Pattern: b, b²/2, b³/3 04Riemann Sums: the Definite Integral and a Year of Loans 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01The Fundamental Theorem of Calculus: Area in One Line 02Net Change and Signed Area: Integrating Velocity 03Six Rules for Definite Integrals and Bounds on eᵇ 04Substitution in Definite Integrals: Change the Limits 問題セット0/10 問題セット20/10 MIT 問題セット0/1

01Average Rate Times Time: FTC Beats the Mean Value Theorem 02Second Fundamental Theorem: Differentiate an Integral 03Proving FTC1 and FTC2 with the Mean Value Theorem 問題セット0/10 問題セット20/10 MIT 問題セット0/2

積分の応用

01The Natural Log Defined as an Area Under 1/t 02Functions With No Formula: erf, Fresnel and Li(x)03Setting Up the Area Between Two Curves 04Vertical vs Horizontal Slices: One Region, Two Integrals 問題セット0/10 問題セット20/10

このページは日本語版を準備中です

The Natural Log Defined as an Area Under 1/t

How can every property of the logarithm, from L(ab) = L(a) + L(b) to the number e, follow from defining it as an area under 1/t?

日本語版の動画は準備中です（英語版を表示しています）

読み込み中…

←前へ Proving FTC1 and FTC2 with the Mean Value Theorem 次へ Functions With No Formula: erf, Fresnel and Li(x) →

まとめノート

1. The definition $L(x) = \int_1^x \frac{dt}{t}$ for $x > 0$
  Write the definition, apply FTC2 to get $L'(x) = \frac{1}{x}$ , evaluate $L(1) = 0$ , and state that these two facts together determine $L$ uniquely.
2. The graph of $L$ and the definition of $e$
  Compute $L''(x) = -\frac{1}{x^2}$ , record that $L$ is increasing and concave down through $(1, 0)$ with slope $1$ , sketch the graph, and define $e$ by $L(e) = 1$ .
3. The sign of $L(x)$ for $0 < x < 1$
  Write out both arguments that $L(x) < 0$ there: one from $L(1) = 0$ with $L$ increasing, and one by reversing the limits to get $-\int_x^1 \frac{dt}{t}$ .
4. The property $L(ab) = L(a) + L(b)$
  Split $\int_1^{ab} \frac{dt}{t}$ at $a$ , substitute $t = au$ in the second piece with the limits changed to $1$ and $b$ , and carry it through to $L(b)$ .
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