Originally Posted by

**jairtime** In this book I'm reading, there are three problems I'm having a hard time with.

1. $\displaystyle \sqrt{12}\times\sqrt{5}=\sqrt{60}=2\sqrt{15}$

When I enter $\displaystyle \sqrt{12}\times\sqrt{5}$ on my TI-84+ and hit Enter, I get 7.745966692 instead.

2. $\displaystyle 3\sqrt{2}\times4\sqrt{8}=12\sqrt{16}=48$

When I enter $\displaystyle 3\sqrt{2}\times4\sqrt{8}$ on my TI-84+ and hit Enter, I get 48, so that answer agrees with the book.

3. $\displaystyle 2\sqrt{10}\times6\sqrt{5}=12\sqrt{50}=60\sqrt{2}$

When I enter $\displaystyle 2\sqrt{10}\times6\sqrt{5}$ on my TI-84+ and hit Enter, I get 84.85281374 instead.

Can anybody explain why my answer is different and what the book's answer means?

Roger