1. What is the value of the expression $\sqrt{11^2}$? The value is ___.
2. Calculate the value of $\sqrt{(-9)^2}$. The result is ___.
3. For which values of the variable $a$ is the equation $\sqrt{a^2} = a$ always true?
4. Which of the following expressions is equivalent to $\sqrt{(-15)^2}$?
5. Simplify the expression: $\sqrt{10^2} + \sqrt{(-4)^2}$. The result is ___.
6. Simplify the expression $\sqrt{5} \cdot \sqrt{10}$. The result is ___.
7. Which expression is equivalent to $(3\sqrt{3})(2\sqrt{12})$?
8. Simplify the expression $(\sqrt{8y})(\sqrt{2y^5})$. The simplified form is ___.
9. Which expression is the result of simplifying $(\sqrt{12x})(\sqrt{3x})$?
10. Calculate the product of $(2\sqrt{6})(4\sqrt{15})$ and simplify completely. The result is ___.