Help me please i need help.

A boundary stripe 6 in. wide is painted around a rectangle whose dimensions are 120 ft by 230 ft. Use differentials to approxima

Nimfa-mama [501]

Answer:

350 square feet

Step-by-step explanation:

We are given that

Width of strip=6 in

Dimension of rectangle= $20 ft\times 230 ft$

We know that

Area of rectangle ,A=xy

Differentiate

$dA=\frac{\partial A}{\partial x}x+\frac{\partial A}{\partial y}y$

We have $\frac{\partial A}{\partial x}=y=230 ft$

$\frac{\partial A}{\partial y}=x=120$

$dx=\frac{12}{12}=1 ft$

1 ft=12 in

Because 6 in added in both side of breadth

dy= $\frac{12}{12}=1 ft$

Because 6 in added on both sides of length of rectangle

Substitute the values

$dA=230\times 1+120\times 1=350 ft^2$

Hence, the number of square feet of paint in the strip=350 square feet

7 0

3 years ago

One number is 1 more than 2 times another. Their product is 10. Find the numbers.

Taya2010 [7]

Whenever a problem says "one number" and "another number" we can substitute x and y. for this we have x=2y+1 and xy=1. since we know the value of x (2y+1) we can substitute it for the other equation to get (2y+1)y=10. simplify to get 2y^2+y=10. from here you can do a few methods to solve this, but the simplest in my opinion is by factoring.

In order to factor it must be equal to 0, so we have 2y^2+y-10=0. We factor this and get y=5 (we also get y=-4 but it is an extraneous root). now we can plug that into either equation and find that x=2.

this means our two numbers are 5 and 2

3 0

3 years ago

There are three cans of juice in the refrigerator and three-fourths of a fourth can. Write a mixed number that represents the am

Gemiola [76]

The answer 3 3/4 . Because there are three ( 3 ) whole cans of jucies in the refrigerator and the fourth can of juice is 3/4 . Thats how you get the answer .

6 0

3 years ago

PLEASE ANSWER THIS ASAP!!!!

Anit [1.1K]

Answer:

82 units

Step-by-step explanation:

7 x 3 = 21

21 x 2 = 42

7 x 2 = 14

14 x 2 = 28

2 x 3 = 6

6 x 2 = 12

42 + 28 + 12 = 82

7 0

3 years ago

The illuminance of a surface varies inversely with the square of its distance from the light source.If the illuminance of a surf

VashaNatasha [74]

Answer:

Distance between the surface and source of light will be increased by 6 meters.

Step-by-step explanation:

The illuminance of a surface varies inversely with the square of ts distance from the light source.

Let illuminance of the surface = x lumens per square meter

and distance from a light source = y meter.

Now x ∝ $\frac{1}{y^{2} }$

Or $x=\frac{k}{y^{2} }$ [k = proportionality constant]

Now we will find the value of k.

k = xy²

k = 120×(6)²

k = 4320

We have to calculate the distance of the source if illuminance of the surface is 30 lumens per square meter.

$30=\frac{4320}{y^{2}}$

y² = $\frac{4320}{30}$

y² = 144

y = √144 = 12 meters

So the source of the light will be shifted away from the surface = 12 - 6 = 6 meters.

6 0

2 years ago