Step-by-step explanation:
hey I hope to the mall is to be a part the highest in a few days and reaction is the area of parallel with you and I hope you feel better soon I have
Answer:
8.4 dollars
Step-by-step explanation:
The error is in the resolution of the proportion. In fact, the initial proportion is correct:

where x is the total cost. However, the following step of the resolution is wrong. In fact, the correct resolution is the following:
- Multiplying by x on both sides:

- Multiplying by 3.5 no both sides:

And now we can find x:

So, the total cost is 8.4 dollars.
(a) True. Suppose A is a not a square matrix, with m rows and n columns. Then A² is not defined, because you can't multiply an m×n matrix by another m×n matrix.
(b) False. As an example, consider the matrices


Then both AB and BA are defined, with


In general, you can multiply any m×n by any n×m matrix.
(c) True. Multiplying a m×n matrix by a n×m matrix always yields a m×m matrix, and multiplying a n×m matrix by a m×n matrix always yields a n×n matrix.