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Pepsi [2]
3 years ago
6

An open rectangular box is 4 feet long and has a surface area of 20 square feet. Find the dimensions of the box for which the vo

lume is as large as possible.
Can someone please explain the steps to the answer if you can?
Mathematics
1 answer:
sweet-ann [11.9K]3 years ago
3 0
SA=2H(L+W)+LW for open box
20=2H(4+W)+4(W)
distribute
20=8H+2WH+4W
divide both sides by 2
10=4H+WH+2W
solve for 1 variable, pick W
10-4H=WH+2W
10-4H=W(H+2)
(10-4H)/(H+2)=W

V=LWH
subsitute 4 for V, subsitute H for H and (10-4H)/(H+2) for W
V=(4)(H)(10-4H)/(H+2)
V=(40H-16H²)/(H+2)
find max value
take deritivitive of this thing
V'=-16(H²+4H-5)/((H+2)²)
using sign chart
sign changes from positive to negative at H=1

so at H=1
find W

W=(10-4H)/(H+2)
W=2

the dimeionts are

length=4ft
width=2ft
height=1ft
(the volume is 8 cubic feet)
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Can someone please help and explain
dangina [55]

Answer:

c = 300000 {(1.05)}^{50}

Step-by-step explanation:

The future value formula is FV=PV(1+i)^n, where the present value PV increases for each period into the future by a factor of 1 + i.  value PV increases for each period into the future by a factor of 1 + i. 

fv = pv {(1 + r)}^{n}

fv = future value

pv = present value

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n= period

7 0
2 years ago
Find the sum of 10x^2-10x-610x 2 −10x−6 and x+6x+6.
nevsk [136]

Answer:

10x^2 -623x +2

Step-by-step explanation:

the numbers were put in weird so im not sure if this is the answer you were looking for, but thats what i got

8 0
3 years ago
Marianne has been collecting donations for her biscuit stall at the school summer fayre. There are some luxury gift tins of bisc
LenaWriter [7]
<span>Answer:

Number of luxury gift tins of biscuits sold at £5 each: 18
Number of normal packets sold at £1 each: 2
Number of mini- packs of 2 biscuits sold at 10p each: 80

Solution:

Number of luxury gift tins of biscuits sold at £5 each: x
Amount received by the number of luxury gift tins of biscuits sold: £5 x Number of normal packets sold at £1 each: y
Amount received by the number of normal packets sold: £1 y
Number of mini- packs of 2 biscuits sold at 10p each: z
Amount received by the number of 2 biscuists sold: 10p z =£0.1z

She tells Amy that she has received exactly 100 donations in total:
(1) x+y+z=100

A collective value of £100:
Total amount receibed: £5 x + £1 y+ £0.1z= £100 → £ (5x+1y+0.1z)= £100 → 5x+y+0.1z=100 (2)

Her stock of £1 packets is very low compared with the other items:
y<<x
y<<z
Then we can despice the value of "y" and solve for "x" and "z":
y=0:
(1) x+y+z=100→x+0+z=100→x+z=100 (3)
(2) 5x+y+0.1z=100→5x+0+0.1z=100→5x+0.1z=100 (4)

Solving the system of equations (3) and (4) using the substitution method:
Isolating z in equation (3): Subtrating x from both sides of the equation:
(3) x+z-z=100-x→z=100-x

Replacing z by 100-x in the equation (4):
(4) 5x+0.1z=100→5x+0.1(100-x)=100
Eliminating the parentheses:
5x+0.1(100)-0.1x=100→5x+10-0.1x=100
Adding similar terms on the left side of the equation:
4.9x+10=100
Solving for x: Subtrating 10 from both sides of the equation:
4.9x+10-10=100-10→4.9x=90
Dividing both sides of the equation by 4.9:
4.9x/4.9=90/4.9→x=18.36734693

Replacing x=18.36734693 in the equation:
z=100-x→z=100-18.36734693→z=81.63265306

We can round x and z: x=18 and z=81 and solve for y in equations (1) and (2):
(1) x+y+z=100→18+y+81=100
Adding similar terms on the left side of the equation:
99+y=100
Subtracting 99 from both sides of the equation:
99+y-99=100-99→y=1

(2) 5x+y+0.1z=100→5(18)+y+0.1(81)=100→90+y+8.1=100→98.1+y=100→98.1+y-98.1=100-98.1→y=1.9→y=2 different to 1

Suppose y=1. Replacing y=2 in equations (1) and (2):
(1) x+y+z=100→x+1+z=100→x+1+z-1=100-1→x+z=99
(2) 5x+y+0.1z=100→5x+1+0.1z=100→5x+1+0.1z-1=100-1→5x+0.1z=99

Repeating the process:
z=99-x
5x+0.1z=99→5x+0.1(99-x)=99→5x+9.9-0.1x=99→4.9x+9.9=99→4.9x+9.9-9.9=99-9.9→4.9x=89.1→4.9x/4.9=89.1/4.9→x=18.18367346
z=99-18.18367346→z=80.81632653
x=18 and z=80
(1) x+y+z=100→18+y+80=100→y+98=100→y+98-98=100-98→y=2
(2) 5x+y+0.1z=100→5(18)+y+0.1(80)=100→90+y+8=100→y+98=100→y+98-98=100-98→y=2

Answer:
Number of luxury gift tins of biscuits sold at £5 each: 18
Number of normal packets sold at £1 each: 2
Number of mini- packs of 2 biscuits sold at 10p each: 80 </span>
5 0
3 years ago
Read 2 more answers
Here's a graph of a linear function. write the equation that describes that function.
7nadin3 [17]

Answer:

Step-by-step explanation:

slope intercept form  =>   Y = mx + b  

find m... the slope by using any two points on the line

p1 = (0,5)  by inspection

p2=(4,6)  by inspection

find m  = y2-y1 / x2-x1

      m   = 6 - 5 / 4 - 0  

      m    =1 / 4

then use the slope intercept formula

y = 1/4x + 5      for your answer.  we know b = 5 b/c thats where the line crosses the y axis.

y = \frac{1}{4}x + 5    is the answer

7 0
3 years ago
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xxMikexx [17]

Answer:

The answer is 800

Step-by-step explanation:

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3 0
3 years ago
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