Is 9^x + 9^(-x) = b ?
(1)x > 0 = b
Is is a sufficient condition?
Here is my working:
putting value of b we get
Is 9^x + 9^(-x) = 0 ?
=> 9^x + 1/9^x = 0
=>( 9^2x + 1 ) /9^x = 0
This will be true only if 9^x (is not equal to) 0
and 9^2x = -1 (this is not possible as even power cannot be -ve)
and 9^x cannot be 0.
Hence this provides answer NO to the question and should be sufficeint.
(But the answer is NOT Sufficient)
Can someone please explain where i am going wrong ?
thanks.
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Just to clarify, is statement (1) actually:
x > 0 = b
That's a really weird statement, don't think I've ever seen anything like it before on the GMAT.
If the statement is correct, then I agree with your conclusion that there's no way that
9^x + 9^(-x) = 0
since that would mean that
9^x = -(1/9^x)
and 9 raised to any power is going to be positive.
x > 0 = b
That's a really weird statement, don't think I've ever seen anything like it before on the GMAT.
If the statement is correct, then I agree with your conclusion that there's no way that
9^x + 9^(-x) = 0
since that would mean that
9^x = -(1/9^x)
and 9 raised to any power is going to be positive.
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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Hi Stuart
This is question 142 from official guid 11 (DS section).
Yes it is printed as x>0=b
Dont have the book at this moment with me but as far as i remember, the explanation uses picking values to solve and I wanted to understand mathematically.
can x>0=b be a printing mistake? (i am using edition 11)
OG answer cannot be wrong? can it?
This is question 142 from official guid 11 (DS section).
Yes it is printed as x>0=b
Dont have the book at this moment with me but as far as i remember, the explanation uses picking values to solve and I wanted to understand mathematically.
can x>0=b be a printing mistake? (i am using edition 11)
OG answer cannot be wrong? can it?