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Zorluk: Çok zorMatrices and Matrix Operations

A company sells two types of gift baskets: Standard and Premium. The sales at the company's North and South branches are represented by matrix SS:

S=[1281510]S = \begin{bmatrix} 12 & 8 \\ 15 & 10 \end{bmatrix}

where the rows represent the North and South branches, respectively, and the columns represent the number of Standard and Premium baskets sold, respectively. The cost of the items inside each basket is represented by matrix CC:

C=[x2430y]C = \begin{bmatrix} x & 24 \\ 30 & y \end{bmatrix}

where the rows represent Standard and Premium baskets, respectively, and the columns represent the cost of food items and the cost of gift items (in dollars), respectively. If the total food item cost at the North branch is 600600 and the total gift item cost at the South branch is 760760, what is the value of x+yx + y?

Cevap: 70

Cevap

The value of x+yx + y is 70.
To find the total costs, the sales matrix SS is multiplied by the unit cost matrix CC. The product matrix R=SCR = SC is a 2×22 \times 2 matrix where the entry in Row 1, Column 1 represents the total food cost at the North branch, and the entry in Row 2, Column 2 represents the total gift cost at the South branch. Setting up the equations 12x+240=60012x + 240 = 600 and 360+10y=760360 + 10y = 760 yields x=30x = 30 and y=40y = 40, which sum to 70.

Adım Adım Çözüm

1
Set up the matrix multiplication R=SCR = SC to represent the total costs.
R=[12x+240288+8y15x+300360+10y]R = \begin{bmatrix} 12x + 240 & 288 + 8y \\ 15x + 300 & 360 + 10y \end{bmatrix}
The product of the sales matrix and the unit cost matrix yields the total cost matrix, where rows represent the branches and columns represent the cost categories.
2
Identify the expression for the total food item cost at the North branch and solve for xx.
x=30x = 30
The total food item cost at the North branch is the entry in Row 1, Column 1 of the product matrix, which is 12x+8(30)=12x+24012x + 8(30) = 12x + 240. Setting this equal to 600600 gives 12x+240=60012x + 240 = 600, which simplifies to 12x=36012x = 360, so x=30x = 30.
3
Identify the expression for the total gift item cost at the South branch and solve for yy.
y=40y = 40
The total gift item cost at the South branch is the entry in Row 2, Column 2 of the product matrix, which is 15(24)+10y=360+10y15(24) + 10y = 360 + 10y. Setting this equal to 760760 gives 360+10y=760360 + 10y = 760, which simplifies to 10y=40010y = 400, so y=40y = 40.
4
Calculate the sum of the variables xx and yy.
x+y=70x + y = 70
Substitute x=30x = 30 and y=40y = 40 into the expression x+yx + y to find the final answer.

Anahtar Kavram

Matrix multiplication and translating real-world scenarios into matrix equations.
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