Adding and subtracting exponents help

Ok, I really need help with his these steps work, and what to do ect. I have no idea what to do when it comes toadying or subtracting exponents, I just know that the index, and radicands must be the same, what do I do if they are different, what do I do if there is no coefficient ct. The question is the square root of seven, minus the square root oof 28 plus 3 times the square root of 63.

Re: Adding and subtracting exponents help

Quote:

Originally Posted by

**xXplosionZz** Ok, I really need help with his these steps work, and what to do ect. I have no idea what to do when it comes toadying or subtracting exponents, I just know that the index, and radicands must be the same, what do I do if they are different, what do I do if there is no coefficient ct. The question is the square root of seven, minus the square root oof 28 plus 3 times the square root of 63.

Hint rad28= 2rad7

Re: Adding and subtracting exponents help

Quote:

Originally Posted by

**xXplosionZz** ...The question is the square root of seven, minus the square root oof 28 plus 3 times the square root of 63.

If I understand your question correctly you want to simplify

$\displaystyle \sqrt{7} - \sqrt{28} + 3 \sqrt{63}$

Factor (if possible) and determine partially the square-root:

$\displaystyle \sqrt{7} - \sqrt{4 \cdot 7} + 3 \sqrt{9 \cdot 7}$

You should come out with $\displaystyle 8\sqrt{7}$

Re: Adding and subtracting exponents help

Thank you very much, it was the part where I had to square root the 4 and the 9, then multiply those by the coefficient which I drew a blank, and then proceed to add/ subtract. :D