John mows lawns. He can mow 7 lawns in 5 hours. At this rate, how long would it

Can you please Find 3/4- 75/n

nlexa [21]

Answer:

3n-300/4n

Step-by-step explanation:

8 0

3 years ago

A rectangle initially has dimensions 6 cm by 7 cm. All sides begin increasing in length at a rate of 1 cm/s. At what rate is the

Morgarella [4.7K]

Answer:

49 cm²/s

Step-by-step explanation:

The problem statement tells you what to do.

Write an equation relating A, b, h:

A = bh . . . . . . the equation for the area of a rectangle

Differentiate with respect to t:

dA/dt = (db/dt)h + b(dh/dt) . . . . . . . product rule

To find the rate of change after 18 seconds, you need to know the dimensions b and h after 18 seconds. Since each dimension was increasing at the rate of 1 cm/s, it is 18 cm more than it was at the beginning:

At 18 seconds,

b = 6 cm + 18 cm = 24 cm;

h = 7 cm + 18 cm = 25 cm.

Of course, db/dt = dh/dt = 1 cm/s. Then the rate of change of area is ...

dA/dt = (1 cm/s)(25 cm) + (24 cm)(1 cm/s)

dA/dt = 49 cm²/s

_____

You could write a formula for the area as a function of time and differentiate that:

A = (6 +t)(7 +t) = 42 + 13t + t²

Then the derivative is ...

dA/dt = 13 +2t

and when t=18, this is ...

dA/dt = 13 + 2(18) = 49 . . . . cm²/s

7 0

3 years ago

A 100g apple is placed on a table. What is the force in newtons of the apple on the table?

abruzzese [7]

Answer:

1N

Step-by-step explanation:

Assuming acceleration of gravity=10m/s²

Force=100/1000kg×10m/s²=1N

5 0

2 years ago

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The length of a concrete slab is three more than three times the width. It's area is 330 square feet. What is the length of the

marin [14]

Answer:

Width: 10.5 feet

Length: 31.5 feet

Step-by-step explanation:

Let x represent width of the concrete slab.

We have been given that the length of a concrete slab is three more than three times the width. So length of the slab would be $3x$ .

We are also told that the area of slab is 330 square feet. We can represent this information in an equation as:

$x\cdot 3x=330$

$3x^2=330$

$x^2=\frac{330}{3}$

$x^2=110$

Now, we will take square root of both sides.

$\sqrt{x^2}=\sqrt{110}$

$x=10.488\approx 10.5$

Therefore, the width of slab is approximately 10.5 feet.

The length of the slab would be $3x\Rightarrow3(10.5)=31.5$ .

Therefore, the length of slab is approximately 31.5 feet.

6 0

3 years ago

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An 8-sided die is formed when two square pyramids are attached by their bases. The perimeter of the base shape is 6 centimeters.

Leona [35]

Consider one pyramid
Side length of base = 1.5cm and its height is 1 cm
Slant height of one of the lateral faces = sqrt(1^2 + 0.75^2) = 1.25 cm
Area of one of the triangular faces = 0.5 * 1.5* 1.25 = 0.9375 cm^2

There are 8 of these so the required surface area = 8 * 0.9375
= 7.5 cm^2 Answer

5 0

3 years ago

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