Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
2x(x-1)/2 + 4(12-x)(12-x-1)/2 + 1.5x(12-x)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random