(b) If
[tex]\[ \left(\begin{array}{cc} -1 & 2 \\ 2 & -2 \end{array}\right) \times P = \binom{-2}{4}, \][/tex]
find the matrix [tex]\( P \)[/tex].



Answer :

To find the matrix [tex]\( P = \begin{pmatrix} p_1 \\ p_2 \end{pmatrix} \)[/tex], we need to solve the system of linear equations given by:

[tex]\[ \begin{pmatrix} -1 & 2 \\ 2 & -2 \end{pmatrix} \begin{pmatrix} p_1 \\ p_2 \end{pmatrix} = \begin{pmatrix} -2 \\ 4 \end{pmatrix} \][/tex]

This system can be written as two equations:
1. [tex]\(-1 \cdot p_1 + 2 \cdot p_2 = -2\)[/tex]
2. [tex]\(2 \cdot p_1 - 2 \cdot p_2 = 4\)[/tex]

Let's solve these equations step-by-step.

Step 1: Solve the first equation for [tex]\( p_1 \)[/tex]

[tex]\[ -1 \cdot p_1 + 2 \cdot p_2 = -2 \][/tex]

Rearranging for [tex]\( p_1 \)[/tex]:

[tex]\[ -1 \cdot p_1 = -2 - 2 \cdot p_2 \][/tex]

So,

[tex]\[ p_1 = 2 + 2 \cdot p_2 \][/tex]

Step 2: Substitute [tex]\( p_1 \)[/tex] into the second equation

Substitute [tex]\( p_1 = 2 + 2 \cdot p_2 \)[/tex] into the second equation:

[tex]\[ 2 \cdot (2 + 2 \cdot p_2) - 2 \cdot p_2 = 4 \][/tex]

Expanding and simplifying:

[tex]\[ 4 + 4 \cdot p_2 - 2 \cdot p_2 = 4 \][/tex]

[tex]\[ 4 + 2 \cdot p_2 = 4 \][/tex]

Step 3: Solve for [tex]\( p_2 \)[/tex]

Subtract 4 from both sides:

[tex]\[ 2 \cdot p_2 = 0 \][/tex]

[tex]\[ p_2 = 0 \][/tex]

Step 4: Solve for [tex]\( p_1 \)[/tex]

Now substitute [tex]\( p_2 = 0 \)[/tex] back into the equation [tex]\( p_1 = 2 + 2 \cdot p_2 \)[/tex]:

[tex]\[ p_1 = 2 + 2 \cdot 0 \][/tex]

[tex]\[ p_1 = 2 \][/tex]

Thus, the matrix [tex]\( P \)[/tex] is:

[tex]\[ P = \begin{pmatrix} 2 \\ 0 \end{pmatrix} \][/tex]