X=-1
Trust me yurrrrrrrrrr
Hello there! You can do something like this:
Kelly has 3/4 cup of a bottle of water. She likes to drink 5 times the amount of that every day. How many cups of water does Kelly like to drink every day?
Hope this helped you!
Good luck!
Answer:
44?
Step-by-step explanation:
Answer: The cost of each game is $2.50
Step-by-step explanation:
Let's find the equations for each friend:
Friend 1:
Pays $3 for the shoes, and plays 3 games, then if X is the cost of each game, Friend 1 pays a total of:
$3 + 3*X
Friend 2:
This friend buys a soda for $0.50, and he plays 4 games, remember that the cost of each game was X. then this friend pays:
$0.50 + 4*X
And we know that both friends pay the exact same amount, then we can write:
$3 + 3*X = $0.50 + 4*X
And solve this for X.
We need to isolate X, then we can move all the terms with X to the right, and all the terms without X to the left:
$3 - $0.50 = 4*X - 3*X
$2.50 = (4 - 3)*X = X
This means the cost of each game is $2.50
The coefficient matrix is build with its rows representing each equation, and its columns representing each variable.
So, you may write the matrix as
![\left[\begin{array}{cc}\text{x-coefficient, 1st equation}&\text{y-coefficient, 1st equation}\\\text{x-coefficient, 2nd equation}&\text{y-coefficient, 2nd equation} \end{array}\right]](https://tex.z-dn.net/?f=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D%5Ctext%7Bx-coefficient%2C%201st%20equation%7D%26%5Ctext%7By-coefficient%2C%201st%20equation%7D%5C%5C%5Ctext%7Bx-coefficient%2C%202nd%20equation%7D%26%5Ctext%7By-coefficient%2C%202nd%20equation%7D%20%5Cend%7Barray%7D%5Cright%5D%20%20)
which means
![\left[\begin{array}{cc}4&-3\\8&-3\end{array}\right]](https://tex.z-dn.net/?f=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D4%26-3%5C%5C8%26-3%5Cend%7Barray%7D%5Cright%5D%20%20)
The determinant is computed subtracting diagonals:
![\left | \left[ \begin{array}{cc}a&b\\c&d\end{array}\right]\right | = ad-bc](https://tex.z-dn.net/?f=%20%5Cleft%20%7C%20%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcc%7Da%26b%5C%5Cc%26d%5Cend%7Barray%7D%5Cright%5D%5Cright%20%7C%20%3D%20ad-bc%20)
So, we have
![\left | \left[\begin{array}{cc}4&-3\\8&-3\end{array}\right] \right | = 4(-3) - 8(-3) = -4(-3) = 12](https://tex.z-dn.net/?f=%20%5Cleft%20%7C%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D4%26-3%5C%5C8%26-3%5Cend%7Barray%7D%5Cright%5D%20%5Cright%20%7C%20%3D%204%28-3%29%20-%208%28-3%29%20%3D%20-4%28-3%29%20%3D%2012%20%20)
