Given:
Expression is

To prove:
If r is any rational number, then
is rational.
Step-by-step explanation:
Property 1: Every integer is a rational number. It is Theorem 4.3.1.
Property 2: The sum of any two rational numbers is rational. It is Theorem 4.3.2.
Property 3: The product of any two rational numbers is rational. It is Exercise 15 in Section 4.3.
Let r be any rational number.
We have,

It can be written as

Now,
3, -2 and 4 are rational numbers by property 1.
is rational by Property 3.
are rational by Property 3.
is rational by property 2.
So,
is rational.
Hence proved.
The answer would be 640. To find the number of how many copies are produced in 1 minute you have to write 80 divided by 5 which equals 16. Now you multiply 16 and the 40 minutes which gives you 640 copies.
The square root of 5/2 is 2.236067978. The square root of 18 is 4.242640687. The total of 2.236067978 plus 4.242640687= 6.478708667.
If you rounded up to two decimal points. You will get 6.48. It depends what digit your question is telling you to round up to.
Hope it helps.
Answer:
0.5
Step-by-step explanation:
First, we need to find how far ahead Marshall was. Since he had been biking at 20 mph for one hour, he had gone 20 miles.
Next, we need to find how long it will take Brett to catch up to Marshall. In order to do this, we need to find how much faster Brett is going than Marshall. We do this by subtracting Marshall's speed from Brett's speed.
60 - 20 = 40. So, Brett is catching up to Marshall at 40 mph. Now, we figure out how long it will take for someone going 40 miles per hour to go 20 miles. We find this by dividing 40 miles per hour by 20. This is equal to 1/2 hour. So, it will take Brett 0.5 hours to catch up to Marshall. This is the same as A, so A is the correct answer.
We can check our answer by seeing how far Marshall and Brett will have gone. Marshall will have been biking for 1.5 hours, so we multiply 20 * 1.5 = 30. Marshall went 30 miles.
Brett drove for .5 hours at 60 mph, so he went 30 miles. Since Brett and Marshall went the same distance, our answer is correct.
The way calculate the volume is l*w*h, 3 times 5 times 7 is 105
Answer: D. 105 km^3