 ## how to multiply and divide rational numbers?

what are the steps? how do i know if they are suppose to be negative or positive? for example:
-3.6 x 4.9 =?
or a harder one is -0.04 / (-0.82) x 1.34
what are the steps to get to the answer? and how would i be able to do this on a calculator?

Odd number of negative signs means negative , even means positive

and be careful of typing…is the 2nd : { ( – 0.04 ) / ( – 0/82) } x 1.34 OR

( – 0.04 ) / { – 0.82 x 1.34 } ?…different answers… ## I need some help evaluating an integral?

This integral is giving me trouble. The problem is to integrate t(cos(sin t))dt from -1 to 1. I know that the answer will be zero since this is an odd function, but I’m wondering if there is any way to do this without graphing the curve.

There is no elemntary anti-derivative for this function so fundamental theorem of calculus cannot be applied.

Riemann sums form -1 to 1 will eventually be 0 by symmetry.
So maybe it is interesting to find integral from 0 to 1
That is
lim sum 1/n f(x_k), where
f(x)=x cos(sin(x)) and x_k=k/n
But I dont know how to that
With calculator that is 0.404… ## Is something being calculated wrong concerning my final grade?

So basically I just took an exam in school and I got a 75% – which is worth 20% of my grade. My overall grade was an 88% and once my exam was put in it went down to a 83%. Does that seem right for that big of a drop?? I used a grade calculator and they said to get an 83% I would have needed to get a 68% on my exam..so why is my grade so low?

Lets see:

.8(88) + .2(75) = x
70.4 + 15 = x
85.4 = x
It does seem rather odd to me, might have to do with how your tests and quizzes are weighted. ## What power consumption calculator should I believe?

I am planning to build a computer and I have already chosen all my components but the power supply and to do so I entered the info about my components in three different power consumption calculators but I got very different numbers from two of the calculators to the another one.

http://www.extreme.outervision.com/PSUEngine, in this calculator I got 276 watts as the result
http://www.thermaltake.outervision.com/Power, in this one I got 266 watts
http://support.asus.com/powersupply.aspx, and in this I got 450 watts

Isn’t it a little odd?, but I think I am doing it the same way in all of them…

I would do the calculation again the first two are probably correct you have to allow a tolerance of about 5 to 10% as Thats the tolerance of Components like Resistors, Capacitors, Inductors.

Its probably using Ohms law to calculate any way the first two are probably correct. Buts its always good to run the calculation again to confirm the results. ## How big of a cage do i need for 2 rats?

I heard rats like to be with other rats is this true and how big of a cage should i buy for two rats?

Try the Ratty Cage Calculator!
Http://www.rattycorner.com/odds/calc.shtml

For rats, the BIGGER the cage is, the better!!

If you are now looking for a cage, try Martins Cages. I bought my rat cage from them and I think it’s great. They also have a toy and supply section which I also love! 🙂
http://www.martinscages.com/