Linear Combinations of Vectors. Bases
When you say a point is at $(3, 5)$, you are actually saying something more concrete: to get there you move $3$ times the vector $(1, 0)$ and $5$ times the vector $(0, 1)$. Those two vectors are a basis, and they are not the only possible ones: any pair of non-parallel vectors can describe the whole plane. How do we know which ones work, and how do we write points using them?
Linear combination
Calculate the coordinates of the vector resulting from the linear combination $3\vec{a} - 2\vec{b}$, knowing that $\vec{a} = (1, 4)$ and $\vec{b} = (-2, 5)$.
Calculate the coordinates of the vector resulting from the linear combination $3\vec{a} - 2\vec{b}$, knowing that $\vec{a} = (1, 4)$ and $\vec{b} = (-2, 5)$.
Knowing that $\vec{w} = 2\vec{u} + k\vec{v}$, with $\vec{u} = (1, -1)$, $\vec{v} = (0, 3)$ and $\vec{w} = (2, 7)$, find the value of the scalar $k$.
Knowing that $\vec{w} = 2\vec{u} + k\vec{v}$, with $\vec{u} = (1, -1)$, $\vec{v} = (0, 3)$ and $\vec{w} = (2, 7)$, find the value of the scalar $k$.
The attached plane shows the vectors $\vec{u}$ and $\vec{v}$. Determine the coordinates of the resultant vector $\vec{z} = 2\vec{u} - \vec{v}$ in the standard basis.
The attached plane shows the vectors $\vec{u}$ and $\vec{v}$. Determine the coordinates of the resultant vector $\vec{z} = 2\vec{u} - \vec{v}$ in the standard basis.
Vector between two points
Why? To go from $A$ to $B$ you move $x_2-x_1$ horizontally and $y_2-y_1$ vertically. That is exactly what the vector says.
Given the parallelogram $ABCD$ in the figure, express the vectors corresponding to the diagonals $\vec{AC}$ and $\vec{BD}$ as a linear combination of the side vectors…
Given the parallelogram $ABCD$ in the figure, express the vectors corresponding to the diagonals $\vec{AC}$ and $\vec{BD}$ as a linear combination of the side vectors $\vec{u} = \vec{AB}$ and $\vec{v} = \vec{AD}$.
Given the points $A(1, 2)$, $B(4, -1)$ and $C(x, y)$, determine the coordinates of the point $C$ knowing that the vectors $\vec{u} = \vec{AB}$ and $\vec{v} = \vec{AC}$…
Given the points $A(1, 2)$, $B(4, -1)$ and $C(x, y)$, determine the coordinates of the point $C$ knowing that the vectors $\vec{u} = \vec{AB}$ and $\vec{v} = \vec{AC}$ form a basis of the plane in which the vector $\vec{w} = (0, -6)$ has coordinates $(2, -1)_B$.
Linear dependence and independence
Given the vectors $\vec{u} = (2, -3)$ and $\vec{v} = (-4, 6)$, mathematically justify whether they can form a basis for the vector space $\mathbb{R}^2$.
Given the vectors $\vec{u} = (2, -3)$ and $\vec{v} = (-4, 6)$, mathematically justify whether they can form a basis for the vector space $\mathbb{R}^2$.
Determine the value of the parameter $m$ such that the vectors $\vec{p} = (m, 4)$ and $\vec{q} = (3, -2)$ are linearly dependent.
Determine the value of the parameter $m$ such that the vectors $\vec{p} = (m, 4)$ and $\vec{q} = (3, -2)$ are linearly dependent.
To guarantee the stability of a node in a planar lattice structure, the direction vectors of two concurrent bars must be linearly independent. The design vectors are…
To guarantee the stability of a node in a planar lattice structure, the direction vectors of two concurrent bars must be linearly independent. The design vectors are $\vec{d}_1 = (k+1, 3)$ and $\vec{d}_2 = (2, k)$. Determine for which values of the parameter $k$ the node is unstable (the vectors do not form a basis). Subsequently, assuming $k=0$, express the external load vector $\vec{P} = (4, -6)$ as a linear combination of $\vec{d}_1$ and $\vec{d}_2$.
Basis of the plane
Express the vector $\vec{c} = (5, -2)$ as a linear combination of the standard basis vectors $\vec{i} = (1, 0)$ and $\vec{j} = (0, 1)$.
Express the vector $\vec{c} = (5, -2)$ as a linear combination of the standard basis vectors $\vec{i} = (1, 0)$ and $\vec{j} = (0, 1)$.
In the physics engine of a video game, the movement of a character is defined in a basis $B = \{\vec{u}, \vec{v}\}$, where $\vec{u} = (2, 1)$ and $\vec{v} = (-1, 3)$. If…
In the physics engine of a video game, the movement of a character is defined in a basis $B = \{\vec{u}, \vec{v}\}$, where $\vec{u} = (2, 1)$ and $\vec{v} = (-1, 3)$. If the character must move to the point indicated by the vector $\vec{d} = (8, -3)$ relative to the standard basis, what will be the coordinates of the displacement vector in the basis $B$?
A logistics company uses two types of vans. The load capacity of type A vans is represented by the vector $\vec{a} = (3, 2)$, indicating 3 pallets of fruit and 2 of…
A logistics company uses two types of vans. The load capacity of type A vans is represented by the vector $\vec{a} = (3, 2)$, indicating 3 pallets of fruit and 2 of vegetables. Type B is represented by $\vec{b} = (1, 4)$. If a shopping center places an exact order of 11 pallets of fruit and 14 of vegetables, represented by $\vec{p} = (11, 14)$, find the scalars of the linear combination $\vec{p} = x\vec{a} + y\vec{b}$ to determine how many trips each van needs to make.
Orthogonal and orthonormal bases
Check whether the set of vectors $B = \{(-1, 2), (2, 1)\}$ forms an orthogonal basis for the plane.
Check whether the set of vectors $B = \{(-1, 2), (2, 1)\}$ forms an orthogonal basis for the plane.
Check whether the vectors $\vec{u} = (3, 0)$ and $\vec{v} = (0, -2)$ form an orthogonal basis for $\mathbb{R}^2$.
Check whether the vectors $\vec{u} = (3, 0)$ and $\vec{v} = (0, -2)$ form an orthogonal basis for $\mathbb{R}^2$.
Determine a vector $\vec{v}$ such that the set $B = \{\vec{u}, \vec{v}\}$ forms an orthonormal basis, given that $\vec{u} = \left(\frac{3}{5}, \frac{-4}{5}\right)$. Is…
Determine a vector $\vec{v}$ such that the set $B = \{\vec{u}, \vec{v}\}$ forms an orthonormal basis, given that $\vec{u} = \left(\frac{3}{5}, \frac{-4}{5}\right)$. Is the solution unique? Justify your answer.
Find the values of $a$ and $b$ so that the vectors $\vec{u} = (a, 3)$ and $\vec{v} = (-2, b)$ form an orthogonal basis, given also that the magnitude of the vector…
Find the values of $a$ and $b$ so that the vectors $\vec{u} = (a, 3)$ and $\vec{v} = (-2, b)$ form an orthogonal basis, given also that the magnitude of the vector $\vec{u}$ is exactly $5$.
Let $\vec{u}$ and $\vec{v}$ be two non-zero vectors such that the angle between them is $60^\circ$, with $|\vec{u}| = 2$ and $|\vec{v}| = 3$. If the vector…
Let $\vec{u}$ and $\vec{v}$ be two non-zero vectors such that the angle between them is $60^\circ$, with $|\vec{u}| = 2$ and $|\vec{v}| = 3$. If the vector $\vec{w} = m\vec{u} + n\vec{v}$ is defined, calculate the relation that must exist between the parameters $m$ and $n$ so that the vector $\vec{w}$ is perpendicular to the vector $\vec{u}$.
The arm of an industrial robot moves in a plane defined by a basis $B = \{\vec{e}1, \vec{e}2\}$ which is orthogonal but not orthonormal, where $|\vec{e}1| = 2$ and…
The arm of an industrial robot moves in a plane defined by a basis $B = \{\vec{e}_1, \vec{e}_2\}$ which is orthogonal but not orthonormal, where $|\vec{e}_1| = 2$ and $|\vec{e}_2| = 4$. A path command instructs it to move according to the vector $\vec{v} = 3\vec{e}_1 - \frac{1}{2}\vec{e}_2$. Calculate the exact magnitude of the displacement vector $\vec{v}$ and the cosine of the angle it forms with the basis vector $\vec{e}_1$.
Change of basis
An underwater drone moves in an environment with ocean currents. Its autonomous navigation system uses a basis formed by the vectors $\vec{c}1 = (1, 2)$ and…
An underwater drone moves in an environment with ocean currents. Its autonomous navigation system uses a basis formed by the vectors $\vec{c}_1 = (1, 2)$ and $\vec{c}_2 = (-2, 3)$. The drone records a displacement $\vec{w}$ whose coordinates in this basis are $(4, -1)_B$. Calculate the coordinates of the vector $\vec{w}$ in the standard basis.
Two tugboats pull a disabled ship with forces $\vec{F}1 = (300, 400)$ N and $\vec{F}2 = (400, -300)$ N. A third tugboat joins by applying a force…
Two tugboats pull a disabled ship with forces $\vec{F}_1 = (300, 400)$ N and $\vec{F}_2 = (400, -300)$ N. A third tugboat joins by applying a force $\vec{F}_3 = (1000, 500)$ N. Express the force $\vec{F}_3$ as a linear combination of the vectors $\vec{F}_1$ and $\vec{F}_2$, finding the coordinates of $\vec{F}_3$ in the basis $B = \{\vec{F}_1, \vec{F}_2\}$.
Prove analytically that if $B = \{\vec{u}, \vec{v}\}$ is a basis of vectors in the plane, then the set $B' = \{\vec{u} + \vec{v}, \vec{u} - \vec{v}\}$ also forms a…
Prove analytically that if $B = \{\vec{u}, \vec{v}\}$ is a basis of vectors in the plane, then the set $B' = \{\vec{u} + \vec{v}, \vec{u} - \vec{v}\}$ also forms a basis. If a vector $\vec{w}$ has coordinates $(3, 5)$ in the basis $B$, find its coordinates in the new basis $B'$.
In the regular hexagon $ABCDEF$ with center $O$ shown in the figure, the basis vectors $\vec{u} = \vec{AB}$ and $\vec{v} = \vec{AF}$ are defined. Express the vectors…
In the regular hexagon $ABCDEF$ with center $O$ shown in the figure, the basis vectors $\vec{u} = \vec{AB}$ and $\vec{v} = \vec{AF}$ are defined. Express the vectors $\vec{AC}$, $\vec{AD}$, $\vec{AE}$ and $\vec{BC}$ as a linear combination of the basis $B = \{\vec{u}, \vec{v}\}$.
In the study of a two-dimensional crystal lattice, two bases are defined for the plane: the primitive basis $B_1 = \{\vec{a}1, \vec{a}2\}$ and a secondary basis…
In the study of a two-dimensional crystal lattice, two bases are defined for the plane: the primitive basis $B_1 = \{\vec{a}_1, \vec{a}_2\}$ and a secondary basis $B_2 = \{\vec{b}_1, \vec{b}_2\}$. Knowing that $\vec{b}_1 = 2\vec{a}_1 - \vec{a}_2$ and $\vec{b}_2 = \vec{a}_1 + 3\vec{a}_2$, find the coordinates in the basis $B_1$ of a point defect whose position vector in the basis $B_2$ is $\vec{d} = (-1, 2)_{B_2}$.
Find all vectors $\vec{x} = (x_1, x_2)$ that, when expressed as a linear combination of the basis $B = \{(1, -1), (2, 1)\}$, have coordinates $(a, b)B$ such that $a = b$…
Find all vectors $\vec{x} = (x_1, x_2)$ that, when expressed as a linear combination of the basis $B = \{(1, -1), (2, 1)\}$, have coordinates $(a, b)_B$ such that $a = b$ and, furthermore, satisfy that their magnitude in the standard basis is exactly $\sqrt{45}$.
Back to the beginning: the point $(3,5)$ is $3\hat\imath+5\hat\jmath$, and any other pair of independent vectors describes the plane just as well, only with different coordinates.