Answer with Step-by-step explanation:
We are given that A and B are two countable sets
We have to show that if A and B are countable then 
is countable.
Countable means finite set or countably infinite.
Case 1: If A and B are two finite sets
Suppose A={1} and B={2}
={1,2}=Finite=Countable
Hence, is countable.
Case 2: If A finite and B is countably infinite
Suppose, A={1,2,3}
B=N={1,2,3,...}
Then, ={1,2,3,....}=N
Hence, is countable.
Case 3:If A is countably infinite and B is finite set.
Suppose , A=Z={..,-2,-1,0,1,2,....}
B={-2,-3}
=Z=Countable
Hence, countable.
Case 4:If A and B are both countably infinite sets.
Suppose A=N and B=Z
Then,=
=Z
Hence, is countable.
Therefore, if A and B are countable sets, then is also countable.
Answer:
B
Step-by-step explanation:
First create the equation that has slope of -1 in the form of y=mx+b. Because the slope is -1, m=-1, so the equation is y=-x+b. Now we see that we are given the point (-3, 8) as an intersection point. Substitute x and y for -3 and 8 in our equation. With this information, our equation becomes 8=3+b. Solving, b=5. Our equation is now y=-x+5.
Simplifying all of the answer choices, we have
A. y=-x-5
B. y=-x+5
C. y=-x-5
D. and E. as what they already show
The only answer that matches is B.
Answer: V=πr^2h=π·4^2·8≈402.12386cm^2
A right triangle must satisfy this equation: a^2 + b^2 = c^2
a= shortest length
b=medium length
c=the longest length
a triangle with sides 4,5,6 will satisfy not this equation because:
4^2 + 5^2 ≠ 6^2
16+25 = 41
41 ≠ 36
so the answer is C.
Hope this helps.
-Jabba
Answer:
Ella has the greatest return in the current year.
Step-by-step explanation:
Debby would receive $0.80 for each of her 2000 common stock in the oil company,hence Debby's return on investment in the current year is $1600($0.80*2000)
Besides,Ella's return on the stock investment in the current year is computed thus:
Ella's return= 5%*1000*$50=$2,500
In addition,Unique's dollar return on the investment is computed as follows:
Unique's return on investment=4%*2000*$20=$1,600
From the above computations,Ella seems to have the highest return in the current year of $2,500 whereas the two others managed to have $1600 return each
