Independence
- Any
two-dimensional linearly independent vectors will span . The two-dimensional basis vectors and are linearly independent, which is why they span . - Any
two-dimensional linearly independent vectors will span . The two-dimensional basis vectors , and are linearly independent, which is why they span . - Any
-dimensional linearly independent vectors will span . The -dimensional basis vectors are linearly independent, which is why they span .
Thereβs no linear independent set that conaints the zero vector.
Dependence
- When
two-dimensional vectors lie along the same line (or along parallel lines), theyβre called collinear, theyβre linearly dependent, and they wonβt span . - When
two-dimensional vectors lie along the same plane, theyβre called coplanar, theyβre linearly dependent, and they wonβt span . - When
-dimensional vectors lie along the same -dimensional space, theyβre linearly dependent, and they wonβt span .
(In)dependence in two dimensions
A set of vectors are linearly dependent when one vector in the set can be represented by a linear combination of the other vectors in the set. Put in another way, if one or more of the vectors in the set doesnβt add any new information or directionality, then the set is linearly dependent.
In
Linearly Dependent Example
When the only difference between two vectors is a scalar, then they liee on the same line, theyβre collinear, and we say that theyβre linearly dependent.
Itβs also helpful to think about linear dependence as the existence of one or more redundant vectors.
Linearly Independant Example
Thereβs no scalar you can multiply by
Which means these vectors arenβt collinear, and they therefore span
Testing for linear (in)dependence
In a plane
We set up a system of equations that include the vectors in the set, and one constant term for each vector.
For example, given the vectors
weβd setup the equation
Then we can break the equation into a system of equations,
then solve the system. In this case, we find
Whether the system is linearly dependent or independent is determined by the values of
In three-dimensional plane
To test for linear independence in three dimensions, we can use the same method we used in two dimensions, which was setting the sum of the linear combination of the vectors equal to the zero vector, and then solving the system.