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2 years ago

13

The perimeter of a square is 20 ft. If you increase the length of the square by 2 feet and decrease the width by 1 foot, what is

the area, in square feet, of the new figure?

2 answers:

Mariulka [41]2 years ago

4 0

Technically, you can't do that because a square has equal side lengths

Tanzania [10]2 years ago

3 0

The perimeter of a square is found by just adding the lengths of the sides together. Since the square has four sides you just divide 20 by 4 to get 5 the length of each side. Then just add 2 to 5 to get the length of 7 and then subtract 1 from 5 to get 4 for the width. The new figure is going to be a rectangle so to find its area it's just width x length. 7 x 4 = 28 ft^2

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A rectangle box with a square base and no top needs to be made using 300ft^2 of material. Find the dimensions of the box with th

Yuri [45]

The dimensions of the box are 10 ft and 5 ft

The maximum volume is 500 ft³

Step-by-step explanation:

A rectangle box with

A square base and no top
It needs to be made using 300 ft² of material
It has greatest volume

Surface area of a box without top (SA) = perimeter of base × height + area of the base

Volume of a box (V) = base area × height

Assume that the length of the side of the square base is x and the height of the box is y

∵ It needs to be made using 300 ft² of material

∴ The surface area of the box is 300 ft²

∵ Its base is a square of side length x ft

∴ Perimeter of the base = 4 × x = 4 x

∴ Area of the base = x²

∵ The height of the box = y ft

∵ SA = perimeter of base × height + area of the base

∵ SA = (4x)(y) + x²

∴ SA = 4xy + x²

∵ SA of the box = 300 ft²

- Equate the two expressions of SA

∴ 4xy + x² = 300

Now let us find y in terms of x

- Subtract x² from both sides

∴ 4xy = 300 - x²

- Divide each term by 4x to find y

∴ $y=\frac{75}{x}-\frac{1}{4}x$

∵ V = area of the base × height

∴ V = x² × y = x²y

- Substitute y by the equation of it above

∴ $V=x^{2}(\frac{75}{x}-\frac{1}{4}x)$

∴ $V=75x-\frac{1}{4}x^{3}$

∵ The volume of the box is greatest

- That means differentiate V and equate it by 0

∵ $\frac{dV}{dx}=75-\frac{3}{4}x^{2}$

∵ $\frac{dV}{dx}=0$ ⇒ greatest volume

∴ $75-\frac{3}{4}x^{2}=0$

- Subtract 75 from both sides

∴ $-\frac{3}{4}x^{2}=-75$

- Divide both sides by $-\frac{3}{4}$

∴ x² = 100

- Take √ for both sides

∴ x = 10

Substitute the value of x in the equation of y

∵ $y=\frac{75}{10}-\frac{1}{4}(10)$

∴ y = 5

The dimensions of the box are 10 ft and 5 ft

∵ $V=75x-\frac{1}{4}x^{3}$

∵ x = 10

∴ $V=75(10)-\frac{1}{4}(10)^{3}$

∴ $V=750-\frac{1}{4}(1000)$

∴ V = 750 - 250

∴ V = 500 ft³

The maximum volume is 500 ft³

Learn more:

You can learn more about the volume in brainly.com/question/6443737

#LearnwithBrainly

6 0

2 years ago

Which graph represents the function f(x)=−3x+7

zepelin [54]

It's be a line that crosses the y-axis at (0,7) and has a slope of -3 or -3/1.

4 0

2 years ago

What is the value of g(f(-5))?

fredd [130]

Replace x in the equation for f(x) with -5:

|2x +9| = |2(-5) +9| = |-10 +9| = |-1| = 1

Now find x 1 and see where the graph of G(x) crosses the Y :

It crosses ay Y = 5

The answer is A. 5

8 0

2 years ago

Please HELLLLP! I will mark brainliest!

Anuta_ua [19.1K]

36-(b^2+c^2-2bc)=36-(b-c)^2=6^2-(b-c)^2= (6+b-c)[6-(b-c)]=(6+b-c)(6-b+c)

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2 years ago

Help question attached multiple choice

Rina8888 [55]

ANSWER

$x = \frac{\pi}{2} , \frac{7\pi}{6} , \frac{3\pi}{2} , \frac{11\pi}{6}$

EXPLANATION

The given trigonometric equation is

$\cos(x) + 2 \cos(x) \sin(x) = 0$

We factor cos(x) to get:

$\cos(x) (1 + 2 \sin(x) ) = 0$

Apply the zero product property to obtain:

$\cos(x) = 0 \: or \: 1 + 2 \sin(x) = 0$

$\cos(x) = 0 \: or \: \sin(x) = - \frac{1}{2}$

Using the unit circle,

$\cos(x) = 0$

when

$x = \frac{\pi}{2}$

and

$x = \frac{3\pi}{2}$

We know

$\sin(y) = \frac{1}{2}$

when

$y= \frac{\pi}{6}$

The sine function is negative in the third and fourth quadrants.

$x = \pi + \frac{\pi}{6} = \frac{7\pi}{6}$

$x = 2\pi - \frac{\pi}{6} = \frac{11\pi}{6}$

Hence the solutions are:

$x = \frac{\pi}{2} , \frac{7\pi}{6} , \frac{3\pi}{2} , \frac{11\pi}{6}$

6 0

2 years ago