Arnold V. answered 04/16/20
Experienced Tutor in Math and Physics with PhD in Physics
Q1.1
T(v1, v2) = (v1 + v2, v1 - v2)
T(3, -14) = (3 - 14, 3+14) = (-11, 17).
w = (3, 19) = T(v1, v2). Therefore, we get a system of two linear equations
v1 + v2 = 3
v1 - v2 = 19.
The solution is (v1, v2) =(11, -8).
Q1.2
T(v1, v2, v3) = (v2 - v1, v1 + v2, 2v1)
T(2, 3, 0) = (3 - 2, 3 + 2, 2.2) = (1, 5, 4).
w = (-11, -1, 10) = (v2 - v1, v1 + v2, 2v1). Therefore, we get a system of three linear equations
-v1 + v2 = -11
v1 + v2 = -1
2v1 = 10.
The solution is v1 = 5, v2 = -6 and v3 can be any number because it not a variable of the equations.
Q2.1
Let us assume that T(x, y) = (x, 1) is a linear transformation. Then
T(ax, ay) = aT(x, y) = a(x, 1) = (ax, a).
However, by the definition
T(ax, ay) = (ax, 1).
This contradiction proves that T(x, y) = (x, 1) is not a linear transformation.
Q2.2
It is easy to check that for T(x, y, z)=(x+y, x-y, z)
T(aR1 + bR2) = aT(R1) + bT(R2).
Here R1 = (x1, y1, z1) and R2 = (x2, y2, z2). Therefore, the transformation is linear.
Q3.
T(0, 3, -1) = 0. T(1, 0, 0) + 3 T(0, 1, 0) - T(0, 0, 1) = 3(1, 3, -2) - (0, -2, 2) = (3, 11, -8).
Q4.1
A is a 3x4 matrix. Hence, it should apply to 4-dimensional vector and produce 3-dimensional vector. Thus n = 4 and m = 3.
Q4.2
A is 3x2 matrix. Hence n = 2 and m = 3.