The mean is calculated by adding up all of the given numbers and dividing by the number of numbers.
Lets, for ease of understanding, say that the first three number were 64...
Mean=(64+64+64)/3=192/3=64
Now, lets solve for the mean where 'x' is the unknown fourth number and 128 is the mean. (since, the answer said that when the fourth number was added the mean, 64, was doubled '64*2=128')
128=(64+64+64+x)/4
128=(192+x)/4
Multiply both sides by 4
512=192+x
subtract 192 from both sides
320=x
The missing number is 320..
Now lets double check our work.
Mean=(64+64+64+320)/4=512/4=128
Answer=320
Answer :
Let's assume the opposite of the statement i.e., 3 + √5 is a rational number.


Since, a, b and 3 are integers. So,

Here, it contradicts that √5 is an irrational number.
because of the wrong assumption that 3 + √5 is a rational number.

Hence, 3 + √5 is an irrational number.
That is the Community Property of Multiplication.
Hope that helps :)
Answer:
x=2.
Step-by-step explanation:
It is given that points A, B, and C are collinear. Point B is between A and C.
Using segment addition property, we get

It is given that AC = 3x + 3, BC = 3, and AB = 2x + 2.


Isolate variable terms.


Therefore, the value of x is 2.