Answer:
No
Step-by-step explanation:
Let's check the first statement with an example. 2 and 3 are positive numbers and their sum (5) is also positive so his first statement is true.
To check the second statement let's look at the negative numbers -1 and -8 for example. Their sum (-9) is also negative so his second statement is true.
To check the third statement let's look at the numbers 9 and -5. One is positive and one is negative, but their sum (4) is positive, so his third statement is false. However if we look at the numbers 4 and -7, their sum is negative so the third statement is partially false.
Answer:
The third option is correct.
The domain of the function is given by

The range of the function is given by

Step-by-step explanation:
Sara bought a cell phone for $200 and its value has decreased at rate of $5 per month.
V(t) is the value of the phone and t is the number of months.
The domain of the function is the possible values of the number of months t.
The domain of the function is given by

The range of the function is the values of V(t) that we get after substituting the possible values of the number of months t.
The range of the function is given by

When the number of months is t = 0 then the value of the function is maximum V(t) = 200
When the number of months is t = 40 then the value of the function is minimum V(t) = 0
Therefore, the third option is correct.
Answer:
For cobalt-60, which has a half-life of 5.27 years, 50% remains after 5.27 years (one half-life), 25% remains after 10.54 years (two half-lives), 12.5% remains after 15.81 years (three half-lives), and so on.
Step-by-step explanation:
You can figue out the rest.
Answer: She earned 868,5 in total last week.
Step-by-step explanation:
18 x 40 = 720 --> earned during the first 40 hours of work
27 x 5,5 = 148,5
148,5 + 720 = 868,5--> total