Chapter 5 Questions!!!

[Rosie]

Oh, okay. I guess it just becomes dauntiing when you are given equations that look impossible to do. I know the main log laws.

[Rosie]

Q7. 3x = 10^-0.3x
You said to type this on calculator. Can you do this by hand or another way.

[Rosie]

I have a sac on Monday relating to chapters 1-5 and I really want to do well.

[Mao]

you can try to simply this by hand (but not actually get to anywhere)
since this is a multiple choice, you'll definitely be able to use your calculator (in the second exam or SAC)

[i tried to simplify this by hand, and cannot yield an appropriate answer. CAS couldnt give me an exact solution either, it cannot be solved by hand (at least not with methods knowledge, if at all)]

this is definitely a calculator problem.

if you are using CAS:

Code: [Select]

solve(3x=10^(-0.3x),x)

and on the 84, you can use the solver:

Code: [Select]

0=10^(-0.3x)-3xor do it graphically:

Code: [Select]

y1=3x
y2=10^(-0.3x)
and find the point of intersection

GL on your SAC

[Rosie]

I put a previous problem on the solver, 84 plus calculator and now I can't remove it. Can you help?

[Rosie]

Also for question 10.
3log₂x - 7log₂(x-1) = 2 + log₂y
log₂x^3/(x-1)^7 = log₂2² + log₂y
right so far?

[Mao]

Also for question 10.
3log₂x - 7log₂(x-1) = 2 + log₂y
log₂x^3/(x-1)^7 = log₂2² + log₂y
right so far?

yep

the right hand side can look slightly better:



and I have no idea about how the technicalities with TI-84... I dont own one.

[Rosie]

Damn, that's okay.
What do I do next?

[Mao]

[Rosie]

 = log₂x^3/(x-1)^7 = log₂2² + log₂y
 = log₂x^3/(x-1)^7 = log₂4y
 = log₂x^3/(x-1)^7 = 4y
y = x^3/4(x-1)^7

Thanks for the help
I would have never been able to do those questions! 

[Glockmeister]

I put a previous problem on the solver, 84 plus calculator and now I can't remove it. Can you help?

Wouldn't have a clue. I've never needed to use solver myself.

[Rosie]

Does anyone else know how to use a solver to remove a previous equation?

[mark_alec]

Does anyone else know how to use a solver to remove a previous equation?

Assuming it is like the 83+, you just press the 'up' arrow after selecting 0: Solver... in the [MATH] menu.