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3 years ago

A DVD is on sale for $1.05 off. This is a 15% discount from the original price. Use an equation to find the origina

Mathematics

1 answer:

Novay_Z [31]3 years ago

6 0

Step by step answer question equation

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Find the volume of the cone

aivan3 [116]

Answer:

12π

Step-by-step explanation:

Volume of the cone is πr^2 * h / 3

r = 3

h = 4

9π * 4 / 3 = 12π

6 0

2 years ago

Read 2 more answers

Paula has two fish tanks that are leaking. The first fish tank hold 50 gallons of water and is leaking at a rate of 5 gallons pe

sergey [27]

Answer:what is the question

Step-by-step explanation:

5 0

2 years ago

DIscrete Math

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

2 years ago

she walks up 9 flights of stairs. If there are 13 steps in 1 flight of stairs, how many steps does Kay climb in 5 days at work?

Lena [83]

13 * 9
And then multiply that answer by 5.

6 0

3 years ago

Read 2 more answers

Find the volume of the rectangular prism

HACTEHA [7]

Answer:

421.875