Evaluate the given expression. ${}_9{P}_4$

You want to arrange the books on your bookshelf by color. How many different ways could you arrange 12 books if 4 of them have a blue cover, 3 are yellow, and 5 are white?

How many ways are there to arrange the letters in the word CALCULUS?

From a class of 28 students, in how many ways could a teacher select 4 students to lead the class discussion?

Find the term indicated in each expansion. (x − 1/2)⁹; fourth term

Find the term indicated in each expansion. (x² + y³)⁸; sixth term

Find the term indicated in each expansion. (x − 1)⁹; fifth term

Find the term indicated in each expansion. (2x + y)⁶; third term