8 - 15 means subtract the positive number 15 from 8.
8 - 15 = 8 + (-15) = -7
8 - (-15) means subtract the negative number -15 from 8.
Subtracting a negative number is the same as adding a positive number.
8 - (-15) = 8 + 15 = 23
8 - 15 = -7, and 8 - (-15) = 23. The expressions mean different operations and have different answers.
The most appropriate choice for maxima and minima of a function will be given by
Rectangle of length 72 feet and breadth 36 feet has largest area
What is maxima and minima?
Maxima of function f(x) is the maximum value of the function and minima of function f(x) is the minimum value of the function.
Here,
Let the length be x feet and breadth be y feet
The farmer has 144 feet of fencing
Three of the sides will require fencing and the fourth wall already exists.
So,
x + y + y =1 44
x + 2y = 144
Area of rectangle(A) = xy 
= (144 - 2y)y
= 

= 
For largest area,



Hence area is maximum
For largest area, y = 36 feet

feet
So length of rectangle is 72 feet, breadth of rectangle is 36 feet
To learn more about maxima and minima of a function, refer to the link:
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From 11 am to 2:15 pm it is 3 hrs and 15 min
For this case we have the following operation:
538 - 247
To subtract both numbers we must follow the following steps:
1) Subtraction is done from left to right:
2) We subtract the first digits:
8 - 7 = 1
3) We subtract the second digits:
3 - 4
Since 4 is greater than 3 then we add a digit to 3 and accumulate it for the next subtraction:
13 - 4 = 9
4) We subtract the digit accumulated in the previous subtraction to the following number:
5 - 2 - 1 = 2
Finally the result is:
538 - 247 = 291
Answer:
Step-by-step explanation:
20/2 + 5/2 = 25/2 = 12 1/2