The term "closed" in math means that if you take two items from a set, do some operation, then you'll always get another value in the same set (sometimes you may get the same value as used before). For example, adding two whole numbers leads to another whole number. We therefore say "the set of whole numbers is closed under addition". This applies to integers as well because integers are positive and negative whole numbers. So we can say that integers are closed under addition.
Integers are not closed under division. Take two integers like 2 an 5 and divide: 2/5 = 0.4 which is not an integer. Integers don't have decimal parts.
The set of whole numbers is {0,1,2,3,...} and we can subtract the two values 1 and 2 to get 1-2 = -1. The order matters here. Subtracting a larger value from a smaller leads to a negative. The value -1 is not in the set of whole numbers. So we can say that whole numbers is not closed under subtraction
Finally, the set of irrational numbers is closed under addition. Adding any two irrational numbers leads to another irrational number. For instance, pi+sqrt(2) = 3.142 + 1.414 = 4.556; I'm using rounded decimals as approximate values. An irrational number is one where we cannot write it as a fraction of integers. Contrast that with a rational number in which we can write it as a fraction of integers. Example: 10 = 10/1 is a rational number.
There are 
of each suit in a deck of 
cards.
This means the probability of drawing a diamond card is 
. You can divide the numerator and denominator each by to simplify. 
Since there are the same number of clubs as there are diamonds, the probabilities are the same.
Hey there!
2/3 = a/30
First: you have to CROSS MULTIPLY the given numbers
2(30) = 3(a)
2(30) = 60
3(a) = 3a
New EQUATION: 3a = 60
Second: DIVIDE 3 to BOTH SIDES
3a/3 = 60/3
CANCEL out: 3/3 because that gives you 1
KEEP: 60/3 because that helps you solve for your a-value
60/3 = a
60/3 = 20
Therefore, your answer is: a = 20
Good luck on your assignment and enjoy your day!
~Amphitrite1040:)
Answer:b
Step-by-step explanation:
Given
Hilda draws a card from a deck of cards and it is seven.
It is certain that card is 7 so there a 4 cards which can be 7
i.e. 7 of hearts,7 of spades,7 of club,7 of diamond
So probability that it is the 7 of spades is
Answer:
y=1/5x+11/5
Step-by-step explanation:
Find the slope of the original line and use the point-slope formula y-y^1=m(x-x^1) to find line parallel to -x+5y=1
Hope this helps
