生成一个10道数学题的练习。


请生成一份包含10个不同类型数学题目的练习，包括加减乘除。
Sure, here are 10 different types of math problems including addition, subtraction, multiplication, and division:

1. 14 - 6 = ?
2. 3/4 * 8 = ?
3. What is the value of pi (π) rounded to two decimal places?
4. (15 + 8) * 2 = ?
5. 90 ÷ 6 = ?
6. 5² + 3³ = ?
7. If a rectangle has a length of 6 cm and a width of 4 cm, what is its area?
8. 27 + (3 * 5) = ?
9. 18 ÷ 3 - 2 = ?
10. Simplify the expression: 2x + 3x² - 4x + 7 - x² - 1.