Category Archives: matematik 4

Partial differential equations

Publicerat den oktober 25, 2012 av mattelararen

A Partial differential equation is a differential equation that contains unknown multivariable functions and their partial derivatives. They are used to formulate problems involving functions of several variables. They can either be solved by hand or used to create a relevant computer … Fortsätt läsa →

Publicerat i Calculus, Gymnasiematematik(high school math), matematik 4 | Märkt , , , , , , , , , , , , | 1 kommentar

Differential equations of the second order

Publicerat den oktober 23, 2012 av mattelararen

Second order differential equations of the homogen type y” (x)+ a y'(x) + by(x) = 0 are possible to solve with the aid of the characteristic equation r2 + a r +b =0 If this have the roots r1 and … Fortsätt läsa →

Publicerat i Calculus, matematik 4, matematik 5 | Märkt | 2 kommentarer

Separable variables

Publicerat den oktober 21, 2012 av mattelararen

Differential equations of the form dy/dx = – P(x)/Q(y) then it is possible to separate the variables Q(y)dy = – P(x) dx → Q(y) dy + P(x) dx = 0 Ex y´+ sinx y = 0 y´ = -sinx y dy/y … Fortsätt läsa →

Publicerat i Calculus, Gymnasiematematik(high school math), matematik 4, Uncategorized | Märkt , | Lämna en kommentar

de Moivre’s formula and complex-conjugation.

Publicerat den september 10, 2012 av mattelararen

(e^ix )^n = cos(nx) + i sin(nx) is called de Moivre’s formula. The formula is named after the 17 th. century French huguenot mathematician Abraham de Moivre. Also the variable in of a function can be a complex number. f(z) … Fortsätt läsa →

Publicerat i Gymnasiematematik(high school math), Imaginary numbers, matematik 4, matematik 5 | Märkt , , , | Lämna en kommentar

Alternative representations of complex numbers

Publicerat den september 9, 2012 av mattelararen

As mentioned in the latest post any complex number may be represented by an arrow in the complex plane. This number is unambiguously described by two numbers: its real part x and its imaginary part y. z= x+iy. This is … Fortsätt läsa →

Publicerat i Imaginary numbers, matematik 4, matematik 5 | Märkt , , , | Lämna en kommentar

Imaginary numbers

Publicerat den september 6, 2012 av mattelararen

A solution to the simple second-degree equation x2 + 1 =0 can not be found along the line of real-numbers. Therefore it was necessary to invent a fictive number i such that i2=-1. i.e. the imaginary numbers making it possible … Fortsätt läsa →

Publicerat i matematik 1c, matematik 4, matematik 5 | Märkt , , , | 2 kommentarer

Properties of integrals

Publicerat den april 11, 2012 av mattelararen

 the integral of a linear combination is the linear combination of the integrals, If a > b then define 3. Additivity of integration on intervals. If c is any element of [a, b], then 4. Upper and lower bounds. An … Fortsätt läsa →

Publicerat i Calculus, matematik 3c, matematik 4 | Märkt | Lämna en kommentar

Definite integrals

Publicerat den april 2, 2012 av mattelararen

In a geometrical context the integral can be interpreted as the area between the graph of the integrand f(x) and the x-axis. The idea is to summarize infinitely many infinitely thin rectangles. (An alternative approach to areacomputation is the Lebesgue-integration where you … Fortsätt läsa →

Publicerat i Calculus, Gymnasiematematik(high school math), matematik 3c, matematik 4 | Märkt | 1 kommentar

Indefinite integrals

Publicerat den mars 28, 2012 av mattelararen

If you need to calculate the distance travelled when you know the velocity as a function of time , since s'(t) = v(t) you need to be able to perform antiderivation i.e. finding a function whose derivative equals your function. … Fortsätt läsa →

Publicerat i Calculus, Gymnasiematematik(high school math), matematik 3c, matematik 4 | Märkt , | Lämna en kommentar

Differentiating the natural logarithm, products and quotients

Publicerat den mars 26, 2012 av mattelararen

In order to be able to deduce the derivative of the natural logarithm we resort to using implicit differentiation. Let x= ey(x) Differentiating both sides gives dx/dx = d ey(x)/dx 1=ey(x) dy(x)/dx Solving for dy(x)/dx one obtains dy(x)/dx = 1/ey(x) … Fortsätt läsa →

Publicerat i Calculus, Gymnasiematematik(high school math), matematik 3c, matematik 4 | Märkt , , | Lämna en kommentar