Strategy Guide 2: Algebra - Solution Problem 6 end of chap

[MaxS693]

Dear,

In the second Strategy Guide (Algebra) on page 103 there is a problem set. It is a DS Question going:
If X=(9b-3ab)/((3/a)-(a/3)), what is X?
(1) (9ab)/(3+a)=18/5
(2) b=1

The solution on page 107 states that the first one is sufficient but not the second statement, so answer A. Since the info in the question stem can be simplified to 9ab(3-a)/((3-a)(3+a)) they say that you can cancel the (a-3) term in both numerator and denominator and then you have the value for x leading to the answer A. But isn’t it true that you cannot cancel out these terms unless you know that a IS NOT equal to 3 because since you don’t know what a is and you only know the info in the question stem and that of statement 1 X could be 18/5 (if a is not equal to zero) or X could be undefined (since we would have 0/0). So actually statement one isn’t sufficient since X could still be two values? Shouldn’t the question stem add something like X is a real number or a not equal to 3 to make this explained solution a correct one?

Thanks in advance!

Kind regards,

Max

[Sage Pearce-Higgins]

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