Error in Harcourt Practice PCAT???

[Wan2BPharmD]

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Okay, it's 3:30 in the morning and I cannot figure this out, and it's driving me nuts. I've always been good at math, but I think I must be missing something. I have the practice PCAT up, and this is the question:

Given that ln e^(2x+1) = 9, what is the value of x?

A. (-1+ln9)/2

B. 4

C. 9/(2*ln e)

D. 23

I'm not going to post what I got, or what they have as the answer. Anyone want to take a stab at this? I'll post their answer a little later. I just want to see what everyone else gets first. Thanks.

 

[k0ni]

A

 

[fenixtnlfan]

B since ln(e^x)=x

Yeah, I actually remembered something from high school!

 

[CaliRx]

Okay, it's 3:30 in the morning and I cannot figure this out, and it's driving me nuts. I've always been good at math, but I think I must be missing something. I have the practice PCAT up, and this is the question:

Given that ln e^(2x+1) = 9, what is the value of x?

A. (-1+ln9)/2

B. 4

C. 9/(2*ln e)

D. 23

I'm not going to post what I got, or what they have as the answer. Anyone want to take a stab at this? I'll post their answer a little later. I just want to see what everyone else gets first. Thanks.

It is def B! ln e=1 therefore 2x+1=9 then you simply solve for x.

 

[CHARMO]

Okay, it's 3:30 in the morning and I cannot figure this out, and it's driving me nuts. I've always been good at math, but I think I must be missing something. I have the practice PCAT up, and this is the question:

Given that ln e^(2x+1) = 9, what is the value of x?

A. (-1+ln9)/2

B. 4

C. 9/(2*ln e)

D. 23

I'm not going to post what I got, or what they have as the answer. Anyone want to take a stab at this? I'll post their answer a little later. I just want to see what everyone else gets first. Thanks.

It's A. See below:

ln e^(2x+1)=ln 9 (Find natural log of both sides)

(2x+1)ln e=ln 9

2x+1 = ln 9 (since ln e=1)

x= (-1+ln9)/2

 

[jojo99]

its A

 

[anh80]

for those of u said "A"..look at the original problem

given: ln e^(2x+1)=9



NOT: ln e^(2x+1)=ln 9



from what's given, it's B. doesn't make any sense if the given problem has "ln" on both sides then it's just 2x+1=ln 9.

 

[CHARMO]

for those of u said "A"..look at the original problem

given: ln e^(2x+1)=9



NOT: ln e^(2x+1)=ln 9



from what's given, it's B. doesn't make any sense if the given problem has "ln" on both sides then it's just 2x+1=9.

Oh! I did not see the ln in the original question. My error.

 

[Knickerbocker]

Yeah, it's almost a trick question because you normally expect to take the ln of both sides for such a problem. In a hurry, you might miss that initial "ln" in front of the "e."

 

[Wan2BPharmD]

Ah, I finally see my mistake. I didn't notice that the "ln" was already in the original equation. The answer is B. I was taking the natural log of both sides. Note to self: stop taking practice tests at 3AM lol =P

Well, at least I wasn't the only one who missed it...even still, I managed to pull of a composite score somewhere in the range of 75th-99th percentile. Gee, that really narrowed it down. Thanks Harcourt, you're the best.

 

[rxgales]

oh sh*txsd, was it lamictal or lamisil? was it glipizide 10 or glyburide 20?....if there is any point or sense or even related

 

[k0ni]

for those of u said "A"..look at the original problem

given: ln e^(2x+1)=9



NOT: ln e^(2x+1)=ln 9



from what's given, it's B. doesn't make any sense if the given problem has "ln" on both sides then it's just 2x+1=ln 9.

Oh crap I missed that "ln" in the front. Haha!

That's what I get for trying to answer the Q after working 8 and 1/2 hours straight (no break!) at work.

 

[nerv12345]

holy hell...short staffed?

 

[k0ni]

holy hell...short staffed?

Yeah, a couple of people are out sick and we're short staffed. I don't even know what I was running on last night. Adrenaline maybe? o__0

 

[acetyl]

The answer is B.

As said before, the ln e part goes away, leaving simple algebra:

ln e^(2x+1)=9
(2x+1)=9
2x=8
x=4

Plus I remember this question and answer from when I took that practice test.

 

[pcproduct]

I say A

e^(2x+1) = 9
lne^(2x+1) = ln9
2x+1 = ln9
2x = ln9-1
x = (ln9-1)/2 = (-1+ln9)/2

 

[Wan2BPharmD]

lol...guys, the answer is B. That is the answer Harcourt gives. The explanations are up above. The original question already takes the natural log of the left side.

 

[TheRxQueen]

To anyone who took the PCAT in June - would this question (or something very similar) be on the test? If so, I'm somewhat relieved. Quickly spotting the natural log in the beginning makes solving the rest of the problem fast! That's a minute and a half I can spend on another problem 👍

 

[islander01]

missing that question probably wont kill you if u can get all the other questions right. i took the pcat back in june, and it is not that bad. i got a 98 on that part, which helped my 22 for reading comp. lolz.