Answer:
Step-by-step explanation:
21-15=6
15 is given
6 is the difference
21-15=6
Step-by-step explanation:
1/2(4a+10)=2a
expand
2a+5=2a
-2a -2a
=5
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.
-2x - 6 < 4
+ 6 + 6
--------------------
-2x < 10
------ -------
-2 -2
x < -5
If you were to graph the solution, the arrow would be going to the left. I know this because the the less than symbol in the answer is pointing to the left. It's kinda hard to tell, but that's the way I figure it out every time. Also, the circle you draw will not be shaded in because the symbol in the answer is greater than or equal to/less than or equal to.
Let me know if any of what I said doesn't make sense. I hope I could help!
7*4=28. Therefore your answer is 28.
Hope this helps.