Final Actually Flashcards
Linear Equation definition
An equation that can be written in the form a1x1+ a2x2+…+anxn =b
Coefficients
Real of complex numbers that are multiplied by x in the linear equation
A system of linear equations (linear system)
A collection of one or more linear equations involving the same variables.
The solution of a system
Is a list of all numbers that makes each equation a true statement when the values of s1,s2,…sn are substituted for x1, x2,… xn respectively.
Solution set
Set of all possible solutions
Equivalent
If they have the same solution set
How many solutions can a system of linear equations have
1) no solutions
2) one solution
3) infinite solutions
Consistent
Has one solution or infinitely many solutions
Inconsistent
No solutions
Coefficient matrix
A matrix of the coefficient of a set of linear equations, does not include answers
Augmented Matrix
The coefficient matrix with an added column containing the constants from the right sides of the equations.
What are the dimensions of an mxn matrix
The matrix has m rows and n columns
Three basic operations to solve linear systems
1) Replace one equation by the sum of itself and a multiple of another equation
2) Interchange two equtions
3) Multiply all terms in an equation by a nonzero constant
Row equivalent
Two matrices are row equivalent if there is a sequence of elementary row operations that transforms one matrix into the other. They will have the same solution set
Two fundamental questions of linear systems:
1) Is the system consistent; that is, does at least one solution exist?
2) If a solution exists, is it the only one; that is, is the solution unique?
Nonzero row or column
A row or columns that contains at least one nonzero entry
Leading entry
Leftmost nonzero entry in a nonzero row
Row Echelon Form REF properties
- All nonzero rows are above any rows of all zeros
- Each leading entry of a row is in a column to the tight of the leading entry of the row above it
- All entries in a column below a leading entry are zeros
Reduce Row Echelon form properties
Same properties as REF plus:
4)The leading entry in each nonzero row is 1
5) Each leading 1 is the only nonzero entry in its column
(Is unique)
Pivot position
A location in A that corresponds to a leading 1 in the reduced echelon form RREF of A
Pivot column
Column that contains a pivot position
Basic variables
Variables of x corresponding to pivot columns.
Free variables
Variables not corresponding to a pivot column
Parameters
Free variables in a parametric equation