Math problem for credits!!

[leo172519]

So I've been trying to help my gf with her math problem but i honestly cannot figure out a possible solution. I decided against putting this in CT because honestly there is no real discussion. Really looking for some help on this if anyone would like to give it a go. Its technically a trig problem, but I apparently cannot come to an answer thats not imaginary.

Heres the equation...

log8(3x^2 - 35.33x + 2622616.88)^.5 = 3

note: that's log base 8.

I used a calculator online and got 7/3 2.66667, but no clue how it got to there.

Thanks to whoever gets it, ill give like 1000 credits if i get an answer soon

[ice_dragon9477]

Re: Math problem for credits!!

looks like a fun problem

but i suck so much at math that i dont even knw what the question is asking for

i used to be good at it when the questions were in the form of 1 + 1 = ? but after that...

sorry cant help

[leo172519]

Re: Math problem for credits!!

lol i know what you mean :P

[foilman8805]

Re: Math problem for credits!!

eh. Rubix is here. he'll answer it.

[knuckles2224]

Re: Math problem for credits!!

lol what?

[bluguerrilla]

Re: Math problem for credits!!

Just solve 8^[log8(3x^2 - 35.33x + 2622616.88)^.5] = 8^3 since it's equivalent to what you have up there.

since n^log_n(z) = z it becomes an easy quadratic. Yay!

P.S. You could even use the log_n(z^(1/2))= 1/2 log_n(z) property first if you like.

Edit: Is that enough of a hint for you?

[bomberboi200]

Re: Math problem for credits!!

LOL

[MrRubix]

Re: Math problem for credits!!

blu: Only problem is that log(x^.5) is not the same as log(x)^.5. For instance, .5*log(5) is the same as log(5^.5) but log(5)^.5 is not the same as .5*log(5)

log8(3x^2 - 35.33x + 2622616.88)^.5 = 3
log8(3x^2 - 35.33x + 2622616.88) = 9
3x^2 - 35.33x + 2622616.88 = 8^9 = 134217728
3x^2 - 35.33x - 131595111 = 0
Now we have ourselves a pretty little quadratic.

a = 3, b = -35.33, c = -131595111

(-b +/- (b^2-4ac)^.5)/2a

Let's start with the first solution (using +)
(-(-35.33) + ((-35.33)^2-4*(3)*(-131595111))^.5)/(2*3) = 6628.9595
Second solution (using -)
(-(-35.33) - ((-35.33)^2-4*(3)*(-131595111))^.5)/(2*3) = -6617.18283

So x can be 6628.9595 or -6617.18283

I haven't done logs in a while but I think this is correct. Anyone who can verify would be more than welcome, lol. It's possible I botched it somewhere.

CREDZ PLZ.

[bluguerrilla]

Re: Math problem for credits!!

Whatever, I assumed he could do the 'simple' stuff. You did pretty much what I told him to do.

I don't solve problems for people, I do enough of that on my own.

Also, like you care about the credits, lol.

[MrRubix]

Re: Math problem for credits!!

I'm gonna be low after my tourney's over -- so I actually could use the credits.

[csoup1414]

Re: Math problem for credits!!

wow, i seriously wish i could help
i am really good at math, but i am only in algebra 2, so yeah
trig next year tho whoo!

[MarukuAntoni]

Re: Math problem for credits!!

dam! i forgot how to do these problems. thats what 1 year away from a math class can do to me.

[leo172519]

Re: Math problem for credits!!

lol thanks rubix i didnt even think about squaring both sides first looks like you win!

EDIT: I tried the way you stated Blu from the start, i just didnt write it out for...some reason...i sent you 100 creds for the help ty

[xinpig]

Re: Math problem for credits!!

posts 6 and 8 lol i dont get any of it

[25thhour]

Re: Math problem for credits!!

Lmao i'm only a grade 8 student. =D Hard ****.