Math

Question Find the y-value of the solution to the 2×22 \times 2 matrix equation [3221][xy]=[34]\left[\begin{array}{ll} 3 & 2 \\ 2 & 1 \end{array}\right]\left[\begin{array}{l} x \\ y \end{array}\right]=\left[\begin{array}{l} 3 \\ 4 \end{array}\right].

Studdy Solution

STEP 1

Assumptions
1. We are given a matrix equation of the form Ax=bA\vec{x} = \vec{b}, where AA is a 2×22 \times 2 matrix, x\vec{x} is a column vector with variables xx and yy, and b\vec{b} is a column vector with constants.
2. We need to solve for the variable yy in the vector x\vec{x}.

The matrix equation is: [3221][xy]=[34] \left[\begin{array}{cc} 3 & 2 \\ 2 & 1 \end{array}\right] \left[\begin{array}{c} x \\ y \end{array}\right] = \left[\begin{array}{c} 3 \\ 4 \end{array}\right]

STEP 2

Write down the system of linear equations represented by the matrix equation.
{3x+2y=32x+y=4 \begin{cases} 3x + 2y = 3 \\ 2x + y = 4 \end{cases}

STEP 3

We will use the method of substitution or elimination to solve the system of equations. Let's first try to isolate yy in the second equation.
y=42x y = 4 - 2x

STEP 4

Substitute the expression for yy from the second equation into the first equation.
3x+2(42x)=3 3x + 2(4 - 2x) = 3

STEP 5

Distribute the 22 into the parentheses.
3x+84x=3 3x + 8 - 4x = 3

STEP 6

Combine like terms.
x+8=3 -x + 8 = 3

STEP 7

Add xx to both sides to isolate the constant term on one side.
8=x+3 8 = x + 3

STEP 8

Subtract 33 from both sides to solve for xx.
x=83 x = 8 - 3

STEP 9

Calculate the value of xx.
x=5 x = 5

STEP 10

Now that we have the value of xx, substitute it back into the expression for yy that we found in STEP_3.
y=42(5) y = 4 - 2(5)

STEP 11

Calculate the value of yy.
y=410 y = 4 - 10

STEP 12

Solve for yy.
y=6 y = -6
The yy-value of the solution to the matrix equation is 6-6.

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