Answer:
Answer for A
Step-by-step explanation:
I don't know about B , Sorry for that.
Answer:
Consider f: N → N defined by f(0)=0 and f(n)=n-1 for all n>0.
Step-by-step explanation:
First we will prove that f is surjective. Let y∈N be any natural number. Define x as the number x=y+1. Then x∈N, and f(x)=x-1=(y+1)-1=y. We conclude that f is surjective.
However, f is not injective. Take x1=0 and x2=1. Then x1≠x2 but f(x1)=0 and f(x2)=x2-1=1-1=0. We have shown that there are two natural numbers x1,x2 such that x1≠x2 but f(x1)=f(x2), that is, f is not injective.
Note:
If 0∉N in your definition of natural numbers, the same reasoning works with the function f: N → N defined by f(1)=1 and f(n)=n-1 for all n>1. The only difference is that you consider x1=1, x2=2 for the injectivity.
1/5 of a foot
Simply subtract the height of Pancho’s sandcastle (3/5 of a foot) minus the height of his sister’s sandcastle (2/5 of a foot) to find a difference of 1/5 of a foot, meaning Pancho’s sandcastle was 1/5 of a foot taller than his sister’s sandcastle.
Answer:
The rectangular 5 x 10 table.
Step-by-step explanation:
To find which table the office manager needs to get so he can sit more people at it is decided by one factor, the perimeter. The rectangular one, which is 5 x 10 the perimeter is (5 x 2) + (10 x 2) = 10 + 20 = 30. The circular one can be calculated by the equation
where d = 8. Putting 
x 8 in my calculator and it comes out approximately at 25.132, having a less amount of perimeter space to work with, making the rectangular table the way to go.
Step-by-step explanation:
37 x 10^2 = 3700
