Calculus

Calculus

Introduction to calculus: what is derivative and Integral

This is a topic ties every things about (functions and graphs) together.

We're mainly concerned with two parts:

1. Derivative (Differentiation)
2. Integrals (Integration)

Derivative is equal to rate of change. Most of the time we will us $dy \over dx$ to present how one variable changes with another. The derivative is the gradient of a tangent line

But from the beginning we are going to talk about where do you want the derivative, the other way to say is I will give you a point and then tell me what's the derivative or gradient for that point.

From the beginning here is the concepts you need for calculus.

1. "what is the derivative at x=n" you can under stand as "what is the gradient when x=n"
2. "What is the Integral at x=a to x=b" you can under stand as "what is the area between the function and the x axis from x=a to x=b".

Conclusion (from the beginning )

derivative = gradient of a tangent = rate of change Integral = area under the function.

Differentiation

Limits

$\lim _{x\to c}f(x)=L,$

Power Rule

$(x^{n})'=n*x^{n-1}$

Derivative of Polynomial Functions

=Newton Derivative of Polynomial Functions=

1. The sum rule $(f+g)'=f'+g'$
2. The Difference Rule $(f-g)'=f'-g'$
3. The Product Rule $(f*g)'=f*g'+g*f'$
4. The Quotient Rule $({f \over g})'={(gf'-fg') \over g^{2}}$

=Leibniz Derivative of Polynomial Functions=

1. The sum rule ${d(f+g) \over dx}={df \over dx}+{dg \over dx}$
2. The Difference Rule ${d(f-g) \over dx}={df \over dx}-{dg \over dx}$
3. The Product Rule ${d(fg) \over dx}'=f{dg \over dx}+g{df \over dx}$
4. The Quotient Rule ${d({f \over g}) \over dx}={g{df \over dx}-f{dg \over dx} \over g^{2}}$

Derivative of Trigonometric Functions

1. $f(sinx)'=cos(x)$
2. $f(cosx)'=-sin(x)$
3. $f(tanx)'=sec^{2}(x)$
4. $f(cotx)'=-csc^{2}(x)$
5. $f(cscx)'=-csc(x)cot(x)$
6. $f(secx)'=sec(x)tan(x)$

Chain Rule

1. Newton Chain rule $[f(g(x))]'=f'(g(x))*g'(x)$
2. Leibniz Chain rule ${\frac {df(g(x))}{dx}}={{df(g)} \over dg}{dg \over dx}$

Derivatives of Logarithmic and Exponential Functions

1. Natural log of $x$ : $(ln(x))'={1 \over x}*(x)'$
2. log of $x$ : $(log_{a}x^{z})'=({lnx^{z} \over lna})'={1 \over ln_{a}}(lnx^{z})'={zx^{z-1} \over ln{a*x^{z}}}$

Higher Derivatives

1. Second derivatives $f''(x)=(f'(x))'$

Newton Higher Derivatives

1. function$f(x)$
2. first derivative $f'(x)$
3. Second derivatives $f''(x)=(f'(x))'$
4. Third derivatives $f'''(x)=(f''(x))'$
5. 4th derivatives $f^{(4)}(x)=(f'''(x))'$

Leibniz Higher Derivatives

1. function $y=f(x)$
2. first derivative ${dy} \over {dx}$
3. second derivatives ${d^{2}}y \over {dx^{2}}$
4. third derivatives ${d^{3}}y \over {dx^{3}}$
5. 4th derivatives ${d^{4}}y \over {dx^{4}}$

Why do we need Higher Derivatives

From the zero derivative to sixth derivative there is a meaning on the graph

1. No derivative function $f(x)$ = Position
2. first derivative $f'(x)$ = Velocity
3. second derivative $f''(x)$ = Acceleration
4. third derivative $f'''(x)$ = Jerk
5. fourth derivative $f^{(4)}(x)$ = Snap
6. fifth derivative $f^{(5)}(x)$ = crackle/flounce
7. sixth derivative $f^{(6)}(x)$ = Pop

How to finding Local Maxima and Minima by Differentiation

Our example will be : $f(x)=x^{3}-12x+1$ And the graph will be the one at the side.

Then we will need to use the derivatives to find the two point that has 0 slope we will also called it Local maxima and Local minima

$f'(x)=3x^{2}-12$

$f'(x)=3x^{2}-12$

$3x^{2}=12$

$x^{2}=4$

Then we get x=2 an x=-2 so the, then we put them into the function.

$f(x)=2^{3}-(12*2)+1=-15$

$f(x)=-2^{3}-(12*-2)+1=17$

so the first point will be local maxima it will be at (-2,17) and then local minima (2,-15).

Graphing Functions and Their Derivatives

1. When a first derivative is positive, the original function is increasing.
2. When a first derivative is negative, the original function is decreasing.
   1. The derivative does not tell us if the function is positive or negative, only if increasing or decreasing.
3. When a second derivative is positive, the original function is concave up.
4. When a second derivative is negative, the original function is concave down.
5. When a first derivative hits zero from below the axis, the original function is at a(n) local minimum.
6. When a second derivative is zero, the original function is at a(n) inflection point.

Limits and L'Hospital's Rule

1. L'Hospital's Rule 1 ${\textstyle \lim _{x\to 0}{f(x) \over g(x)}=lim_{x\to 0}{f'(x) \over g'(x)}}$
2. L'Hospital's Rule 2 ${\textstyle \lim _{x\to \infty }{f(x) \over g(x)}=lim_{x\to \infty }{f'(x) \over g'(x)}}$

Integration

Mathematicians have been playing with the concept of integration for ages, but it was until Newtons time that it was realized that integration and differentiation are inverse operations.

Integral

1. Hint $F'(x)=f(x)$ F(x) is not equal to f(x).
2. Definite Integral $\int _{a}^{b}f(x)\,dx=F(b)-F(a),$
3. Indefinite Integral $\int f(x)\,dx=F(x)+c,$

Properties of Indefinite Integral

1. sum rule of Indefinite Integral $\int [f(x)+g(x)]\,dx=\int f(x)\,dx+\int g(x)\,dx$
2. The Difference Rule $\int [f(x)-g(x)]\,dx=\int f(x)\,dx-\int g(x)\,dx$

Integrals With Trigonometric Functions

1. $\int cosx\,dx=sinx+c$
2. $\int sinx\,dx=-cosx+c$
3. $\int {sec}^{2}x\,dx=tanx+c$
4. $\int {csc}^{2}x\,dx=-cotx+c$
5. $\int secx\,tanx\,dx=secx+c$
6. $\int cscx\,cotx\,dx=-cscx+c$

Integration By Parts

1. Performing Integration By Parts #$\int f(x)g'(x)\,dx=f(x)g(x)-\int f'(x)g(x)\,dx$

Infinity Integral

When you get a Integral like this

1. Definite Integral from a to infinite $\int _{a}^{\infty }f(x)\,dx$
2. Definite Integral from negative infinite to b $\int _{-\infty }^{b}f(x)\,dx$
3. Definite Integral from negative infinite to infinite $\int _{-\infty }^{\infty }f(x)\,dx$

All equations that you may need to know for integration

1. $\int x^{n}\,dx={x^{n+1} \over n+1}$
2. $\int 1 \over x\,dx={ln|x|}$
3. $\int a^{x}\,dx={a^{x} \over lna}$
4. $\int e^{x}\,dx=e^{x}$
5. $\int sinx\,dx=-cosx$
6. $\int cosx\,dx=sinx$
7. $\int secxtanx\,dx=secx$
8. $\int sec^{2}x\,dx=tanx$
9. $\int csc^{2}x\,dx=-cotx$
10. $\int \csc x\cot x\,dx=-cscx$
11. $\int secx\,dx=ln|secx+tanx|$
12. $\int cscx\,dx=ln|cscx-cotx|$
13. $\int tanx\,dx=ln|secx|$
14. $\int cotx\,dx=ln|sinx|$

Definite integrals area under a curve and above the curve

1. Definite Integral under and above the curve $\int _{a}^{b}f(x)\,dx,\int _{b}^{c}|f(x)|\,dx=F(b)-F(a)+|F(b)-F(a)|,$

Area between curves

$\int _{a}^{b}(upperfunction-lowerfunction)\,dx,$

if f(x) = upper function and g(x) = lower function

$\int _{a}^{b}(f(x)-g(x))\,dx,$

Reference

1. IB Maths AA SL/HL calculus
2. Calculus by Professor Dave Explains