Recent content by danne89

In the car he also. So you have two right triangles with a common side, the road to the castle. One has an angle of 30 degrees and a side of 45 km. The other triangle has a angle of 40 degrees and a side of 22.5 km,

I'm sorry. I was in a hurry when I tried to descibe my progress. I indeed draw a picture and obtained those equations above. My point is that they contridict each other.

A car travels with a velocity of 90 km/h on a stright line. And a man in the car saw a castle left of the road. The angle the straight line to the castle from the cars position was 30 degrees. 15 min (same vel) later another man spots the castle in an 40-degrees angle. After another 15 min they...

B/A Isn't so hard if you think about it.

Isn't the combinations of the prime factors = all factors? I mean, i pick 2*2 (a product of the primes in the positions specified by the combination) or 12 i pick 2*2 or 23 i pick 2*3 or 24 and so on. Do you see?

Hi! How do I determine the number of distinct factors of a number, say, 2520? 2520 = 2*2*2*3*3*5*7 So we've 8 different primes. The number of combinations of those is, according to me: C(8,1)+C(8,2)+...+C(8,8)=155 (I think, calculated it by hand; but it isn't important) Obviously those...

I thought it would be useless because the answer must build on his axioms... But here it comes: If x is an arbitrary real number, prove that there exist positive integers such as m<x<n.

Hello! Anyone read Apostol's Calculus vol. 1. On p. 28 the exercises feels very hard. Can somebody help me with nr. 2?

Thanks! You clear a few questionmarks, but created even more. I'll read a book on mathematical logic in the future i think.

There isn't some color one can paint on a wall to get a nice blackboard.

I was watching this new show called numb3rs. The main character is a mathematican and has a some blackboards he is using. http://www.numb3rs.org/gallery/albums/userpics/10002/NUMB3RS_S01E01_033.jpg I couldn't stop wonder if someone in real life is standing like this and write on blackboards...

Hi! I've problem proving a logical statement. I really can nothing about logic. I just messing around with some in a try to prove another theorem. Anyway, I would be useful to be able to prove that: (P_b and not P_1) and ([itex]P_b[/tex] and not [itex]P_2[/tex] and ... as P1, P2, P3 ...

I solved it. I did indeed just need to crack the units.

It's working perfectly. I just expressed myself a little sloppy.

A battery is being charged by a voltage v=11+0.5t V and a constant current of 2 A. The price of a kWh is 10 cent. How much is 5 hours battery-charging? My work: p = 22 + t w= \int_{0}^{5} x dt = 25/5 + 22*5 = 122.5 W 122.5 W in 5 h = 5 * 122.5 Wh = 0.6125 kWh