When the question says "What is the value of..." the question is asking if we have enough information to determine a single value. There are 2 variables in the equation provided (x and y) and S1 only gives us a value for x. The equation is not equal to anything, ti's just an equation. IF THE QUESTON HAD provided the equation of 6x^2 + 9y^2 = 33
, then providing us with the value of a single variable WOULD be enough to find the value of y and therefore would be sufficient, but this information is still missing. Look at every problem as if it has 2 varaibles.
a = b
Sometimes we know one variable, such as a = 2. If a = 2, then b = 2. If we have a more complext problem, we have a^2 + b = c
. Now we have 3 variables. This is similar to the equation given. While the question isn't written with that third variable visible, it is present. Its the variable we're trying to solve for. It 6x^2 + 9y^2 = z
and we need to find z. So anytime you have 3 variables, in order to solve for the entire equation to a single value, you need to know the value of AT LEAST 2 of those variables. [There are exceptions to this, but as a general rule, knowing the information necessary to solve the equation is a vital step in doing Data Sufficiency questions.]
What is the value of the following expression: 6x^2 + 9y^2?
1. x = 2
2. 6y^2 + 4x^2 = 22
* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient
* Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient
* BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
* EACH statement ALONE is sufficient
* Statements (1) and (2) TOGETHER are NOT sufficient
Statement 1 provides us with value of x but it is insufficient to answer the whole question
Statement 2 provides us with necessary information: we need to multiply the second statement times 1.5 and we will get our result: 33 = 9y^2 + 6x^2
How is x = 2 no sufficient? If we know the value for x we can solve for y and then add the two.
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.