If a and b are positive numbers, explain how the value of

(sqrt{a}*sqrt{b})^2 compares with the value of a + b.

I used FOIL and ended up with a + 2(sqrt{ab}) + b, which does not equal a + b.

Results 1 to 7 of 7

- May 5th 2009, 10:12 PM #1

- Joined
- Jul 2008
- From
- NYC
- Posts
- 1,489

- May 5th 2009, 10:30 PM #2

- Joined
- Oct 2005
- From
- Earth
- Posts
- 1,599

- May 5th 2009, 10:53 PM #3

- May 6th 2009, 06:12 AM #4

- Joined
- Jul 2008
- From
- NYC
- Posts
- 1,489

- May 6th 2009, 03:36 PM #5

- May 6th 2009, 05:21 PM #6

- Joined
- Apr 2005
- Posts
- 16,632
- Thanks
- 1924

You used "foil" on what? Of course, a+ 2sqrt{ab}+ b is not equal to a+ b, why should it be? Were you asked to about (sqrt{a}*sqrt{b})^2 or (sqrt{a}+ sqrt{a})^2? And you weren't asked to show these were equal, only to "compare" them. Which is larger, (sqrt{a}+ sqrt{b})^2 or (a+ b)^2?

- May 6th 2009, 07:12 PM #7

- Joined
- Jul 2008
- From
- NYC
- Posts
- 1,489