Discussion
| Column A | Column B | |
 |
0 |
| (A) | Column A is larger |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 09/12/2012 06:27
Why is the answer not d? The square root of 1/9 is 1/3 and -1/3. The former would result in column a being bigger, but the later means column b is bigger. Why is the negative root ignored?
Posted: 09/12/2012 13:50
Lacey, the square root of 1/9 is only 1/3; it doesn't include -1/3.
This is a common mistake that people make. If you are solving for x^2 - 1/9 = 0, that's a different problem, because you can factor out the left hand side to be (x-1/3)(x+1/3) = 0, so that you have two solutions to the problem.
x^2 = 1/9 and x = √1/9 are not the same equations. The first has 2 solutions. The second only has 1 solution. Square roots are always positive.
This is a common mistake that people make. If you are solving for x^2 - 1/9 = 0, that's a different problem, because you can factor out the left hand side to be (x-1/3)(x+1/3) = 0, so that you have two solutions to the problem.
x^2 = 1/9 and x = √1/9 are not the same equations. The first has 2 solutions. The second only has 1 solution. Square roots are always positive.