Answer:
<em>The area of the triangle DEF is 10.</em>
Step-by-step explanation:
<u>Area of a Triangle:</u>
A triangle of base B and height H (both must be perpendicular) has an area of:
The image below shows the triangle formed by the points DEF. It's important to notice the points E and F lie on the same horizontal line because they both have the same y-coordinate.
This fact simplifies the calculations since we can easily compute the length the of base as the difference of their x-coordinates:
B=3-(-2)=3+2=5
Being the base of a horizontal line, the height of the triangle can be calculated as the difference of y-coordinates of D and the height of that line.
H=2-(-2)=4
With these two values, we calculate the area:
The area of the triangle DEF is 10.
Answer:
where 
denotes number of drinks and 
denotes number of pastries.
Step-by-step explanation:
Let denotes number of drinks and denotes number of pastries.
Cost of the average drink = $4.50
Cost of the average pastry = $2.25
Total amount = $5,250
Therefore,
The formula of combination is
We have
and
Hence, there are 1001 ways of arranging 10 records from 14 records
m x H = ![\left[\begin{array}{ccc}-25&37.5&-12.5\\\9\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-25%2637.5%26-12.5%5C%5C%5C9%5Cend%7Barray%7D%5Cright%5D)
Step-by-step explanation:
Step 1; Multiply 5 with this matrix ![\left[\begin{array}{ccc}-1&2\\4&8\\\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-1%262%5C%5C4%268%5C%5C%5Cend%7Barray%7D%5Cright%5D)
and we get a matrix ![\left[\begin{array}{ccc}-5&10\\20&40\\\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-5%2610%5C%5C20%2640%5C%5C%5Cend%7Barray%7D%5Cright%5D)
Multiply the fraction 
with the matrix and we get ![\left[\begin{array}{ccc}-\frac{2m}{5} &\frac{4m}{5} \\\frac{8m}{5} &\frac{16m}{5} \\\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-%5Cfrac%7B2m%7D%7B5%7D%20%26%5Cfrac%7B4m%7D%7B5%7D%20%5C%5C%5Cfrac%7B8m%7D%7B5%7D%20%26%5Cfrac%7B16m%7D%7B5%7D%20%5C%5C%5Cend%7Barray%7D%5Cright%5D)
Step2; Now equate corresponding values of the matrices with each other.
-5 = 
and so on. By equating we get the value of m as 
Step 3; Add the matrices to get the value of matrix m.
Adding the three matrices on the RHS we get ![\left[\begin{array}{ccc}2&9&-9\\\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2%269%26-9%5C%5C%5Cend%7Barray%7D%5Cright%5D)
.
Step 4; Adding the matrices on the LHS we get the resulting matrix as H +
![\left[\begin{array}{ccc}4&6&-8\\\9\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D4%266%26-8%5C%5C%5C9%5Cend%7Barray%7D%5Cright%5D)
. Equating the matrices from step 3 and 4 we get the value of H as ![\left[\begin{array}{ccc}-2&3&-1\\\9\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-2%263%26-1%5C%5C%5C9%5Cend%7Barray%7D%5Cright%5D)
Step 5; Now to find the value of m x H we need to multiply the value of with the matrix
Step 6; Multiplying we get the matrix m x H = [ -25 
]
Step-by-step explanation:
I hope you understand it
