 # Practice Open-Ended Question (10 mins) Keeping Records at the Gas Station Juan has a part-time job at a gas station. Part of his responsibility is to keep.

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Practice Open-Ended Question (10 mins) Keeping Records at the Gas Station Juan has a part-time job at a gas station. Part of his responsibility is to keep track of the sales of stock items. During one week last July he sold the following: 160 quarts of oil at an average price of \$1.45 per quart 25 gallons of antifreeze at \$6.50 per gallon 24 tires at an average price of \$49.75 per tire 4 batteries at a total price of \$140 various auto supply accessories at a total price of \$245.75 A.) What was the total income from the sale of all these items? B.) What percent of sales did the accessories represent? C.) If Juan received a 5% commission on total sales, and a salary of \$100 a week, how much did Juan earn that week? D.) If Juan is offered another job for a salary of \$150 a week without commission, should he quit his current job? Why or why not? Support your answer.

HSPA Prep Lesson 3 Operations on Matrices

row rows A matrix is a rectangular array of numbers. We subscript entries to tell their location in the array Matrices are identified by their size. Matrices and Row Operations

Barnett/Ziegler/Byleen Finite Mathematics 11e 5 Example: Addition Solution Add the matrices Solution: First note that each matrix has dimensions of 3x3, so we are able to perform the addition. The result is shown at right: Adding corresponding entries, we have

6 Example: Subtraction Solution Now, we will subtract the same two matrices Subtract corresponding entries as follows: =

Scalar Multiplication To do this, multiply each entry in the matrix by the number outside (called the scalar). This is like distributing a number to a polynomial.

Scalar Multiplication Example:

To add matrices, we add the corresponding elements. They must have the same dimensions. A + B

When a zero matrix is added to another matrix of the same dimension, that same matrix is obtained.

To subtract matrices, we subtract the corresponding elements. The matrices must have the same dimensions.

Scalar Multiplication: We multiply each # inside our matrix by k.

Barnett/Ziegler/Byleen Finite Mathematics 11e 18 Matrix Equations Example: Find a, b, c, and d so that Solution: Subtract the matrices on the left side: Use the definition of equality to change this matrix equation into 4 real number equations: a - 2 = 4b + 1 = 3c + 5 = -2d - 6 = 4 a = 6b = 2 c = -7d = 10