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Vectors

Magnitude, direction, components, and adding vectors head to tail.

A vector is a quantity with magnitude and direction — displacement, velocity, force. In components it is just a column of numbers, adding entry by entry; its length comes from Pythagoras. Linear algebra picks up here.

Работен пример: [[3],[4]]

Linear-Algebra · Matrices

[[3],[4]]

\left[\begin{matrix}3\\4\end{matrix}\right]

Стъпка по стъпка

  1. \left[\begin{matrix}3\\4\end{matrix}\right]

    A 2×1 matrix.

  2. \operatorname{rank} A = 1

    Rank (number of independent rows).

  3. A^T = \left[\begin{matrix}3 & 4\end{matrix}\right]

    Transpose.

Разкрийте отговора
\left[\begin{matrix}3\\4\end{matrix}\right]

Symbols used here

A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}
matrix
A rectangular array of numbers; a linear map.
\leq,\ \geq
less/greater than or equal
Inequalities that allow equality; < and > exclude it.
|x|
absolute value / modulus
Distance from zero: |−3| = 3. For a complex number, distance from the origin.
\binom{n}{k}
binomial coefficient, "n choose k"
Number of k-element subsets of n things: n!/(k!(n−k)!).
\pi
pi
Ratio of a circle's circumference to its diameter, 3.14159…
e
Euler's number
2.71828…, the base whose exponential is its own derivative.
i
imaginary unit
i² = −1.
\theta
theta
The usual name for an angle.
\log_b x,\ \ln x
logarithm, natural log
The exponent b must be raised to for x; ln uses base e.
\mathbf{v},\ \vec{v}
vector
A quantity with magnitude and direction; a column of numbers.

How to: Vectors

  1. A 2×1 matrix.
  2. Rank (number of independent rows).
  3. Transpose.

Questions people ask

What is a function, really?

A rule that assigns exactly one output to each input. The vertical-line test on a graph is the same idea: no input may have two outputs.

Why do we need complex numbers?

Because x² + 1 = 0 has no real solution, and allowing one new number i with i² = −1 makes every polynomial equation solvable. They then turn out to describe rotation, waves and alternating current more naturally than real numbers do.

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Още в Precalculus

Complex numbersPolynomial functionsRational functionsSequences and seriesThe binomial theoremConic sectionsExponential and logarithmic functionsPolynomial division and the remainder theoremParametric equations and polar coordinates