2 times the square root of 4 is just 4. Then finally, you get f of 6 is square root of 6 minus 1 is the square root of 5. I think we are now ready to evaluate. Let me get my handy TI-85 out and calculate this. It's going to be... I'm just going to calculate... Well, I'll just multiply. 0.5 times, open parentheses, well, it's a 0.