Answer:
[tex]A = \left[\begin{array}{ccc}1&-4&2\\2&6&-6\end{array}\right][/tex]
Step-by-step explanation:
Given
[tex]T:R^3->R^2[/tex]
[tex]T(e_1) = (1,2)[/tex]
[tex]T(e_2) = (-4,6)[/tex]
[tex]T(e_3) = (2,-6)[/tex]
Required
Find the standard matrix
The standard matrix (A) is given by
[tex]Ax = T(x)[/tex]
Where
[tex]T(x) = [T(e_1)\ T(e_2)\ T(e_3)]\left[\begin{array}{c}x_1&x_2&x_3\\-&&x_n\end{array}\right][/tex]
[tex]Ax = T(x)[/tex] becomes
[tex]Ax = [T(e_1)\ T(e_2)\ T(e_3)]\left[\begin{array}{c}x_1&x_2&x_3\\-&&x_n\end{array}\right][/tex]
The x on both sides cancel out; and, we're left with:
[tex]A = [T(e_1)\ T(e_2)\ T(e_3)][/tex]
Recall that:
[tex]T(e_1) = (1,2)[/tex]
[tex]T(e_2) = (-4,6)[/tex]
[tex]T(e_3) = (2,-6)[/tex]
In matrix:
[tex](a,b)[/tex] is represented as: [tex]\left[\begin{array}{c}a\\b\end{array}\right][/tex]
So:
[tex]T(e_1) = (1,2) = \left[\begin{array}{c}1\\2\end{array}\right][/tex]
[tex]T(e_2) = (-4,6)=\left[\begin{array}{c}-4\\6\end{array}\right][/tex]
[tex]T(e_3) = (2,-6)=\left[\begin{array}{c}2\\-6\end{array}\right][/tex]
Substitute the above expressions in [tex]A = [T(e_1)\ T(e_2)\ T(e_3)][/tex]
[tex]A = \left[\begin{array}{ccc}1&-4&2\\2&6&-6\end{array}\right][/tex]
Hence, the standard of the matrix A is:
[tex]A = \left[\begin{array}{ccc}1&-4&2\\2&6&-6\end{array}\right][/tex]