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TheMorningStar
Registered User regular

Ok, so I haven't taken a math course in awhile and I have some chem homework due next week and I just wanted to double check my answer with you guys. I've gone over it a bunch of times, but I still feel like Im making a stupid mistake.

Y = (Z/X) + 2 Solve for X

I came up with YZ - 2Z = X

Also, there's a problem asking for the antilog of -3.8456, how do I do this on my TI-83-plus?

Y = (Z/X) + 2 Solve for X

I came up with YZ - 2Z = X

Also, there's a problem asking for the antilog of -3.8456, how do I do this on my TI-83-plus?

0

## Posts

X=Z/(Y-2)

BoutrosonY = (Z/X) + 2. ---> original

Y - 2 = (Z/X).

> subtract 2 from both sides

X = (Z/Y - 2). ----> switching positions of the (X) and (Y-2)

I think what you did wrong was at the part where Y - 2 = (Z/X).

XanoonI'm pretty certain you just do 10 ^ -3.8456.

I'd rather have someone else confirm it though.

XanoonHow many liters of a 10% alcohol solution must be mixed with 30 liters of a 50% solution to get a 20% solution?

I remember doing a problem almost exactly like this two semesters ago, but now I have no idea where to even start. Help!

I figured it out! Now I just need to do more investigating into the antilog thing...

TheMorningStaronAeroonFor the liters problem, you just need to think that .1x + .5y = .2z where x + y = z, where we know y is 30, so it becomes a system of equations problem with two variables and two equations.

0.1x + 15 = 0.2z

1.0x + 30 = 1.0z

There's a couple of ways to solve this, but I feel kind of weird doing someone else's homework, so I'll let someone else finish up, or tell me I'm doing it totally wrong.

MalyonsusonThe bold part is actually multiplying both sides with X and dividing both sides by (Y-2). You can't do that if Y-2 = 0. So you have to do a special case for Y=2 and exclude it explicitly before doing this operation.

(The special case goes: if Y=2, then 0 = Z/X, so Z=0 and X can be anything.)

Grobianon