Ralph earns 72,000 annually as an architect and is paid semimonthly

Daniel [21]

Answer:

Step-by-step explanation:

As the statement is ‘‘if and only if’’ we need to prove two implications

$f : X \rightarrow Y$ is surjective implies there exists a function $h : Y \rightarrow X$ such that $f\circ h = 1_Y$ .
If there exists a function $h : Y \rightarrow X$ such that $f\circ h = 1_Y$ , then $f : X \rightarrow Y$ is surjective

Let us start by the first implication.

Our hypothesis is that the function $f : X \rightarrow Y$ is surjective. From this we know that for every $y\in Y$ there exist, at least, one $x\in X$ such that $y=f(x)$ .

Now, define the sets $X_y = \{x\in X: y=f(x)\}$ . Notice that the set $X_y$ is the pre-image of the element $y$ . Also, from the fact that $f$ is a function we deduce that $X_{y_1}\cap X_{y_2}=\emptyset$ , and because $f$ the sets $X_y$ are no empty.

From each set $X_y$ choose only one element $x_y$ , and notice that $f(x_y)=y$ .

So, we can define the function $h:Y\rightarrow X$ as $h(y)=x_y$ . It is no difficult to conclude that $f\circ h(y) = f(x_y)=y$ . With this we have that $f\circ h=1_Y$ , and the prove is complete.

Now, let us prove the second implication.

We have that there exists a function $h:Y\rightarrow X$ such that $f\circ h=1_Y$ .

Take an element $y\in Y$ , then $f\circ h(y)=y$ . Now, write $x=h(y)$ and notice that $x\in X$ . Also, with this we have that $f(x)=y$ .

So, for every element $y\in Y$ we have found that an element $x\in X$ (recall that $x=h(y)$ ) such that $y=f(x)$ , which is equivalent to the fact that $f$ is surjective. Therefore, the prove is complete.

3 0

3 years ago

4 • (6 – 4) 2 ÷ 2

Dmitry_Shevchenko [17]

Answer:

Cary is wrong

Step-by-step explanation:

4* (6-4)= 4* 2=8

I think it is saying (8*2) divided by to, which in that case is 8,

but if it is asking 8 (2/2) then that would also be 8 I believe. I really hope this is correct and you have a great day :)

5 0

3 years ago

Read 2 more answers

At the afternoon matinee movie, 2 adult tickets and 4 child tickets cost $32, and 4 adult tickets and 3 child tickets cost $44.

Yuliya22 [10]

Answer:

2x + 4y = 32

4x + 3y = 44

Step-by-step explanation:

From the information supplied in the question, we can see that 2 adult tickets and 4 child tickets cost $32. This means we multiply the cost of an adult ticket by 2 and add it to the product of 4 child tickets and its price I.e y.

We can also see that to get a total cost of $44, 4 adult tickets and 3 child tickets were bought. Hence, we simply multiply the cost of an adult ticket by 4 and add it to the product of 3 child ticket and its price

8 0

3 years ago

A recipe uses 2 cups of milk to make 4 servings. If the same amount of milk is used for each serving, how many servings can be m

iren2701 [21]

Answer:

12 servings

Step-by-step explanation:

Please let me know if you want me to write an explanation for my answer :)

7 0

3 years ago

Find mEC.<br> 5x - 27)<br> (2x - 5)<br> D

UNO [17]

Answer:

Arc EC = 58°

Step-by-step explanation:

First, find the value of x.

m<D = ½(arc EC) => Inscribed Angles Theorem

Substitute

2x - 5 = ½(5x - 27)

Multiply both sides by 2

2(2x - 5) = 5x - 27

4x - 10 = 5x - 27

Collect like terms

4x - 5x = 10 - 27

-x = -17

Divide both sides by -1

x = 17

Find arc EC:

Arc EC = 5x - 27

Plug in the value of x

Arc EC = 5(17) - 27 = 85 - 27

Arc EC = 58°

4 0

3 years ago