Let x = number of months.
Let y = total number of fish in pond.
6% of 3,000 = 180 fish
We can use an equation to help us with this problem.
y = 3,000 + 180x - 400x. Combine like terms.
y = 3,000 - 220x. Plug 9 in for x.
y = 3,000 - 220(9). Solve for y
y = 1,020.
There are 1,020 fish in the pond after 9 months.
Answer:
See explanation
Step-by-step explanation:
Given:
![A=\left[\begin{array}{cc}-2&4\\1&3\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%264%5C%5C1%263%5Cend%7Barray%7D%5Cright%5D)
![B=\left[\begin{array}{cc}-2&1\\3&7\end{array}\right]](https://tex.z-dn.net/?f=B%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%261%5C%5C3%267%5Cend%7Barray%7D%5Cright%5D)
A. Find AB:
![AB=\left[\begin{array}{cc}-2&4\\1&3\end{array}\right]\cdot \left[\begin{array}{cc}-2&1\\3&7\end{array}\right]=\left[\begin{array}{cc}-2\cdot (-2)+4\cdot 3&-2\cdot 1+4\cdot 7\\1\cdot (-2)+3\cdot 3&1\cdot 1+3\cdot 7\end{array}\right]=\left[\begin{array}{cc}16&26\\7&22\end{array}\right]](https://tex.z-dn.net/?f=AB%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%264%5C%5C1%263%5Cend%7Barray%7D%5Cright%5D%5Ccdot%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%261%5C%5C3%267%5Cend%7Barray%7D%5Cright%5D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%5Ccdot%20%28-2%29%2B4%5Ccdot%203%26-2%5Ccdot%201%2B4%5Ccdot%207%5C%5C1%5Ccdot%20%28-2%29%2B3%5Ccdot%203%261%5Ccdot%201%2B3%5Ccdot%207%5Cend%7Barray%7D%5Cright%5D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D16%2626%5C%5C7%2622%5Cend%7Barray%7D%5Cright%5D)
B. Find BA:
![BA=\left[\begin{array}{cc}-2&1\\3&7\end{array}\right]\cdot \left[\begin{array}{cc}-2&4\\1&3\end{array}\right]=\left[\begin{array}{cc}-2\cdot (-2)+1\cdot 1&-2\cdot 4+1\cdot 3\\3\cdot (-2)+7\cdot 1&3\cdot 4+7\cdot 3\end{array}\right]=\left[\begin{array}{cc}5&-5\\1&33\end{array}\right]](https://tex.z-dn.net/?f=BA%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%261%5C%5C3%267%5Cend%7Barray%7D%5Cright%5D%5Ccdot%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%264%5C%5C1%263%5Cend%7Barray%7D%5Cright%5D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D-2%5Ccdot%20%28-2%29%2B1%5Ccdot%201%26-2%5Ccdot%204%2B1%5Ccdot%203%5C%5C3%5Ccdot%20%28-2%29%2B7%5Ccdot%201%263%5Ccdot%204%2B7%5Ccdot%203%5Cend%7Barray%7D%5Cright%5D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D5%26-5%5C%5C1%2633%5Cend%7Barray%7D%5Cright%5D)
C. Answers are not the same
D. Matrices multiplication is not commutastive in general, so
Answer:
the second one for #4 and the third one for #5
Step-by-step explanation:
4. The sum of x and y is 24, so x+y = 24. The difference is 15, so x-y = 15, or
y-x=15 (they didn't specify which was which). Therefore, A, C, and D are correct, so x = 15-y is the answer (x = 15-y is the same as x+y = 15, which is false).
5.
Matt = 6 apple pies + 4 lemon pies and he got 80 dollars.
Ming = 6 apple pies + 5 lemon pies and he got 94 dollars.
If apple pie is "a" and lemon is "l":
6a + 4l = 80
6a + 5l = 94,
so C is the answer
