Use a calculator's factorial key to evaluate each expression. (300/20)!

In Exercises 81–85, use a calculator's factorial key to evaluate each expression.

$\frac{20!}{300}$

Use a calculator's factorial key to evaluate each expression. 20!/(20−3)!

In Exercises 81–85, use a calculator's factorial key to evaluate each expression.

$\frac{54!}{(54-3)!3!}$

Use mathematical induction to prove that each statement is true for every positive integer n. 2 + 4 + 8 + ... + 2ⁿ = 2ⁿ⁺¹ - 2

Use mathematical induction to prove that each statement is true for every positive integer n. 1 + 2 + 2² + ... + 2^n-1 = 2^{n - 1}

Use mathematical induction to prove that each statement is true for every positive integer n. 3 + 7 + 11 + ... + (4n - 1) = n(2n + 1)

Use mathematical induction to prove that each statement is true for every positive integer n. 1 + 3 + 5 + ... + (2n - 1) = n²