Answer:

![B)\,\,A^{-1}=\left[\begin{array}{ccc}7&-1&-1\\-3&1&0\\-3&0&1\end{array}\right]](https://tex.z-dn.net/?f=B%29%5C%2C%5C%2CA%5E%7B-1%7D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%26-1%26-1%5C%5C-3%261%260%5C%5C-3%260%261%5Cend%7Barray%7D%5Cright%5D%20)
Step-by-step explanation:

Expanding with first row
![det(A) = \left\Bigg|\begin{array}{ccc}1&1&1\\3&4&3\\3&3&4\end{array}\right\Bigg|\\\\\\det(A)= (1)\left\Big|\begin{array}{cc}4&3\\3&4\end{array}\right\Big|-(1)\left\Big|\begin{array}{cc}3&3\\3&4\end{array}\right\Big|+(1)\left\Big|\begin{array}{cc}3&4\\3&3\end{array}\right\Big|\\\\det(A)=1[16-9]-1[12-9]+1[9-12]\\\\det(A)=7-3-3\\\\det(A)=1](https://tex.z-dn.net/?f=det%28A%29%20%3D%20%5Cleft%5CBigg%7C%5Cbegin%7Barray%7D%7Bccc%7D1%261%261%5C%5C3%264%263%5C%5C3%263%264%5Cend%7Barray%7D%5Cright%5CBigg%7C%5C%5C%5C%5C%5C%5Cdet%28A%29%3D%20%281%29%5Cleft%5CBig%7C%5Cbegin%7Barray%7D%7Bcc%7D4%263%5C%5C3%264%5Cend%7Barray%7D%5Cright%5CBig%7C-%281%29%5Cleft%5CBig%7C%5Cbegin%7Barray%7D%7Bcc%7D3%263%5C%5C3%264%5Cend%7Barray%7D%5Cright%5CBig%7C%2B%281%29%5Cleft%5CBig%7C%5Cbegin%7Barray%7D%7Bcc%7D3%264%5C%5C3%263%5Cend%7Barray%7D%5Cright%5CBig%7C%5C%5C%5C%5Cdet%28A%29%3D1%5B16-9%5D-1%5B12-9%5D%2B1%5B9-12%5D%5C%5C%5C%5Cdet%28A%29%3D7-3-3%5C%5C%5C%5Cdet%28A%29%3D1)
To find inverse we first find cofactor matrix


Cofactor matrix is
![C=\left[\begin{array}{ccc}7&-3&3\\-1&1&0\\-1&0&1\end{array}\right] \\\\Adj(A)=C^{T}\\\\Adj(A)=\left[\begin{array}{ccc}7&-1&-1\\-3&1&0\\-3&0&1\end{array}\right] \\\\\\A^{-1}=\frac{adj(A)}{det(A)}\\\\A^{-1}=\frac{\left[\begin{array}{ccc}7&-1&-1\\-3&1&0\\-3&0&1\end{array}\right] }{1}\\\\A^{-1}=\left[\begin{array}{ccc}7&-1&-1\\-3&1&0\\-3&0&1\end{array}\right]](https://tex.z-dn.net/?f=C%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%26-3%263%5C%5C-1%261%260%5C%5C-1%260%261%5Cend%7Barray%7D%5Cright%5D%20%5C%5C%5C%5CAdj%28A%29%3DC%5E%7BT%7D%5C%5C%5C%5CAdj%28A%29%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%26-1%26-1%5C%5C-3%261%260%5C%5C-3%260%261%5Cend%7Barray%7D%5Cright%5D%20%5C%5C%5C%5C%5C%5CA%5E%7B-1%7D%3D%5Cfrac%7Badj%28A%29%7D%7Bdet%28A%29%7D%5C%5C%5C%5CA%5E%7B-1%7D%3D%5Cfrac%7B%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%26-1%26-1%5C%5C-3%261%260%5C%5C-3%260%261%5Cend%7Barray%7D%5Cright%5D%20%7D%7B1%7D%5C%5C%5C%5CA%5E%7B-1%7D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D7%26-1%26-1%5C%5C-3%261%260%5C%5C-3%260%261%5Cend%7Barray%7D%5Cright%5D)
Answer:
- 1/5
Step-by-step explanation:
Slope of a line passing through two points can be calculated as:

The given points are (-2, -1) and (8, -3). Using the values in above formula, we get:

Thus the slope of the line through the given points is -1/5. So 2nd option gives the correct answer
x would equal 2 because:
4 times 5 is 20
4 times 2x is -8x
move over the 8x to the side with the 2x
then you have 10x=20
20/10 equals x=2
Hope this helps :)
Answer – A letter
In algebraic equations, a variable refers to an unknown or changeable number. Typically, all the letters in the alphabet are used to represent variables in algebra. Letters from the Greek alphabet are also used in some advanced algebra. Therefore, in algebra, we use a letter to represent a variable.
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