Find the sum of 8756,9094 and 37,065

The central four rectangles down the middle of the net are 9 units wide, and alternate between 8 and 7 units high. Then the area of those four rectangles is ...

9(8+7+8+7) = 270 . . . square units

The rectangles making up the two left and right "wings" of the net are 8 units high and 7 units wide, so have a total area of ...

2×(8)(7) = 112 . . . square units

Then the area of the figure computed from the net is ...

270 +112 = 382 . . . square units

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<em>Additional comment</em>

You can reject the first two answer choices immediately, because they are odd. Each face will have an area that is the product of integers, so will be an integer. There are two faces of each size, so <em>the total area of this figure must be an even number</em>.

You may recognize that the dimensions are 8, 8+1, 8-1. Then the area is roughly that of a cube with dimensions of 8: 6×8² = 384. If you use these values (8, 8+1, 8-1) in the area formula, you find the area is actually 384-2 = 382. That area formula is A = 2(LW +H(L+W)).

3 0

3 years ago

Prove that if r is any rational number, then 3r2 − 2r + 4 is rational. The following properties may be used in your proof. Prope

ziro4ka [17]

Given:

Expression is

$3r^2-2r+4$

To prove:

If r is any rational number, then $3r^2-2r+4$ 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,

$3r^2-2r+4$

It can be written as

$3(r\times r)-2r+4$

Now,

3, -2 and 4 are rational numbers by property 1.

$r^2=r\times r$ is rational by Property 3.

$3r^2\text{ and }-2r$ are rational by Property 3.

$3r^2+(-2r)+4$ is rational by property 2.

So, $3r^2-2r+4$ is rational.

Hence proved.

6 0

3 years ago

Bert is planning to open a savings account that earns 1.6% simple interest yearly. He wants to earn exactly $240 in interest aft

Drupady [299]

I = PRT
I = 240
R = 1.6% = 0.016
T = 3

now we sub and solve for P, the money he should deposit
240 = P * 0.016 * 3
240 = 0.048P
240 / 0.048 = P
5000 = P <==== ur answer is 5,000

5 0

3 years ago