1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Molodets [167]
3 years ago
13

Alex has four books of different sizes which he wishes to place on a bookshelf. Unfortunately, the bookshelf has a conspicuous h

ole at one end through which only the smallest book can fall. If he wishes for all his books to stay stationary, in how many ways can he arrange his books?
Mathematics
1 answer:
vredina [299]3 years ago
6 0
18, you have 3 choices for the bottom because you can't use the small one, 3 choices for the next because you can now use the small one, 2 for the next and finally 1. You multiply all of them to get 18
You might be interested in
I need some really help......
kozerog [31]
Length x width = formula of finding the area of a rectangle

2 3/7 x 2 4/5 = 6 4/5 (6.8)

The area of the rectangle is 6 4/5 / 6.8
3 0
3 years ago
Simplify 3x + 2 (9-5) <br><br>please help....
viktelen [127]
3x+8 
i am pretty sure about that
3 0
3 years ago
Read 2 more answers
Solve x to the second power = 144
vfiekz [6]

x ^ 2 = 144

x = 12, x = -12

Check:

12 * 12 = 144

-12 * -12 = 144

6 0
3 years ago
Read 2 more answers
3) The sum of three consecutive numbers is 72.<br> What are the smallest of these numbers?
Oksi-84 [34.3K]

Answer:

23

Step-by-step explanation:

x+x+1=x+2=72

3x+3=72

3x=69

x=23

23+24+25=72

7 0
3 years ago
A torus is formed by rotating a circle of radius r about a line in the plane of the circle that is a distance R (&gt; r) from th
jeyben [28]

Consider a circle with radius r centered at some point (R+r,0) on the x-axis. This circle has equation

(x-(R+r))^2+y^2=r^2

Revolve the region bounded by this circle across the y-axis to get a torus. Using the shell method, the volume of the resulting torus is

\displaystyle2\pi\int_R^{R+2r}2xy\,\mathrm dx

where 2y=\sqrt{r^2-(x-(R+r))^2}-(-\sqrt{r^2-(x-(R+r))^2})=2\sqrt{r^2-(x-(R+r))^2}.

So the volume is

\displaystyle4\pi\int_R^{R+2r}x\sqrt{r^2-(x-(R+r))^2}\,\mathrm dx

Substitute

x-(R+r)=r\sin t\implies\mathrm dx=r\cos t\,\mathrm dt

and the integral becomes

\displaystyle4\pi r^2\int_{-\pi/2}^{\pi/2}(R+r+r\sin t)\cos^2t\,\mathrm dt

Notice that \sin t\cos^2t is an odd function, so the integral over \left[-\frac\pi2,\frac\pi2\right] is 0. This leaves us with

\displaystyle4\pi r^2(R+r)\int_{-\pi/2}^{\pi/2}\cos^2t\,\mathrm dt

Write

\cos^2t=\dfrac{1+\cos(2t)}2

so the volume is

\displaystyle2\pi r^2(R+r)\int_{-\pi/2}^{\pi/2}(1+\cos(2t))\,\mathrm dt=\boxed{2\pi^2r^2(R+r)}

6 0
3 years ago
Other questions:
  • Plssssssssssss help me<br><br> whats 6 times 1/10?
    5·2 answers
  • 5/6 4/15
    12·1 answer
  • A professional baseball team will play 1 game Saturday and 1 game Sunday. A sportswriter estimates the team has a 60% chance of
    5·1 answer
  • There are 2 miners. One mines 19,687 m of ore in 1 hour and the other one mines the same amount of ore in 51 minutes. Find how m
    7·2 answers
  • Malcolm bought 6 bowls for $13.20. What is the unit rate?
    13·2 answers
  • Answer this for 15 POINTS and BRAINLIEST
    14·1 answer
  • How can you quickly determine the number of roots a polynomial will have by looking at the equation?
    8·2 answers
  • Which statement is true about multiplying exponential expressions?
    12·1 answer
  • What is the range of the first graph &amp; the domain of the second graph ?
    7·2 answers
  • Please solve it this helps me. ​
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!