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3 years ago

12

Dan can tile a floor in 3 hours. his assistant could tile the same floor in 8 hours. if they work together, how long will it tak

e to tile the floor?

1 answer:

natta225 [31]3 years ago

7 0

There is a formula for this:

Total Time = (worker1 * worker2) / (worker1 + worker2)

(3 * 8) / (3 + 8)

24 / 11 =

2.1818181818 hours

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The domain of the function is all<br> The range of the function is all

kondaur [170]

The domain of a function is the set of all the x terms of the function and the range of a function is the set of all the y terms of a function.

For example, take a look below.

The domain is the set of all x terms in each ordered pair and the

range will be the set of all the y terms in each ordered pair.

7 0

3 years ago

Would the scale factor 4.2 enlarge,reduce,or preserve

Juli2301 [7.4K]

Hey there! I'm happy to help!

Let's look at what scale factors would be able to enlarge, reduce, and preserve first. We will use the point (1,1) as an example.

ENLARGE

When we talk about scale factors, both of our numbers of the ordered pair will be multiplied by that number. To make it bigger, we will multiply it by anything larger than a one, we could have a scale factor such as 2, 100, 579395. etc.!

Dilation of 2

(1,1)⇒(2,2)

REDUCE

To reduce our ordered pair, our scale factor must be a number greater than zero but less than one because it cannot switch quadrants, which is what would happen if we used negative numbers. Our reduced number must be greater than zero. We can use 1/2, 1/4, 1/100, 0.67 etc.

Dilation of 1/2

(1,1)⇒(0.5,0.5)

PRESERVE

What would we multiply an ordered pair by to make it stay the same? One of course! This is the only number that will keep it the same!

Dilation of 1

(1,1)⇒(1,1)

Now, let's think of any scale factor as X and see what rules it has to follow to be enlarging, reducing, or preserving.

ENLARGING SCALE FACTOR: X>1

REDUCING SCALE FACTOR: 0<X<1

PRESERVING SCALE FACTOR: X=1

So, where does 4.2 fall? Well, as you can see, 4.2 is greater than one, so this scale factor would make our point larger.

Therefore, 4.2 would enlarge.

I hope that this helps! Have a wonderful day!

8 0

3 years ago

Find 38.01% of 111. Round to the nearest thousandth

Svetllana [295]

Answer:

42.191

Step-by-step explanation:

Punch it in the calculator and round the decimal from 42.1911 to 42.191

3 0

3 years ago

Write the value of 17 tens in standard form

lyudmila [28]

17 tens can be said as 17 x 10
So 17 x 10 is 170
170 is in standard form

3 0

3 years ago

Read 2 more answers

3. The curve C with equation y=f(x) is such that, dy/dx = 3x^2 + 4x +k

Andreas93 [3]

a. Given that y = f(x) and f(0) = -2, by the fundamental theorem of calculus we have

$\displaystyle \frac{dy}{dx} = 3x^2 + 4x + k \implies y = f(0) + \int_0^x (3t^2+4t+k) \, dt$

Evaluate the integral to solve for y :

$\displaystyle y = -2 + \int_0^x (3t^2+4t+k) \, dt$

$\displaystyle y = -2 + (t^3+2t^2+kt)\bigg|_0^x$

$\displaystyle y = x^3+2x^2+kx - 2$

Use the other known value, f(2) = 18, to solve for k :

$18 = 2^3 + 2\times2^2+2k - 2 \implies \boxed{k = 2}$

Then the curve C has equation

$\boxed{y = x^3 + 2x^2 + 2x - 2}$

b. Any tangent to the curve C at a point (a, f(a)) has slope equal to the derivative of y at that point:

$\dfrac{dy}{dx}\bigg|_{x=a} = 3a^2 + 4a + 2$

The slope of the given tangent line $y=x-2$ is 1. Solve for a :

$3a^2 + 4a + 2 = 1 \implies 3a^2 + 4a + 1 = (3a+1)(a+1)=0 \implies a = -\dfrac13 \text{ or }a = -1$

so we know there exists a tangent to C with slope 1. When x = -1/3, we have y = f(-1/3) = -67/27; when x = -1, we have y = f(-1) = -3. This means the tangent line must meet C at either (-1/3, -67/27) or (-1, -3).

Decide which of these points is correct:

$x - 2 = x^3 + 2x^2 + 2x - 2 \implies x^3 + 2x^2 + x = x(x+1)^2=0 \implies x=0 \text{ or } x = -1$

So, the point of contact between the tangent line and C is (-1, -3).

7 0

2 years ago