   Math problem
  I''m trying to brush up my skills in maths so that eventually i can be comfortable with 3d geometry. I have been reading this one book and stumbled on this problem that has plain stumped me, its meant to be grade 8 difficulty and this is why i really want to know what you guys think. If i can''t do grade 8 math then i figure I should give up  Or maybe this is just a really difficult question.----(the * is meant to be a star)if2 * 6 = 44 * 1 = 78 * 3 = 1what is 5 * 5 = --- 
  is that star supposed to represent just some operation to perform on the two numbers....just like a + sign means to add two numbers together the star means to perform some kind of operation or sequence of operations....you just have to figure it out from the numbers giventhat is what i think at least. "A soldier is a part of the 1% of the population that keeps the other 99% free"  - Lt. Colonel Todd, 1/38th Infantry, Ft. Benning, GA ;  2 * 6 = 4 //divide 6 by 3 then add4 * 1 = 7 //multiply 1 by 3 and add5 * 5 = 8 * 3 = 1 //multiply 3 by 3, then subtract (keep absolute value);quote:Original post by tagged  I'm trying to brush up my skills in maths so that eventually i can be comfortable with 3d geometry. I have been reading this one book and stumbled on this problem that has plain stumped me, its meant to be grade 8 difficulty and this is why i really want to know what you guys think. If i can't do grade 8 math then i figure I should give up  Or maybe this is just a really difficult question.----(the * is meant to be a star)if2 * 6 = 44 * 1 = 78 * 3 = 1what is 5 * 5 = ---   Think of star as a function between two numbers.f(2, 6) = 4f(4, 1) = 7f(8, 3) = 1and use those to extrapolatef(5, 5) = [edited by - morris2 on February 2, 2004 8:50:59 AM];quote:Original post by tagged  Or maybe this is just a really difficult question.Indeed it is.Just think about it:you have three argument/value-pairs and three functions.Even provided you just had one argument, e.g. f(x) = y, itwould be far from trivial to figure what f actually is.Without any additional clue, it is nearly impossible tofigure out z = f(x,y) with just three samples (plus the fact that all x, y, z tuples differ for each sample).Could you at least provide us with the context of this question(e.g. what the chapter of the book was about)?;quote:Original post by darookie  quote:Original post by tagged   Or maybe this is just a really difficult question.Indeed it is.Just think about it:you have three argument/value-pairs and three functions.Even provided you just had one argument, e.g. f(x) = y, itwould be far from trivial to figure what f actually is.Without any additional clue, it is nearly impossible tofigure out z = f(x,y) with just three samples (plus the fact that all   x, y, z tuples differ for each sample).Could you at least provide us with the context of this question(e.g. what the chapter of the book was about)? Actually it''s not that hard.The answer is 2.Anyone wanna know why? ;quote:Original post by mbrown211  [Actually it''s not that hard.The answer is 2.Anyone wanna know why?Feel free to enlighten me ;  Ok, if we say that the result, z, is a function of the two operands x and y, this function can be defined as:z = f(x, y) = 12 - (x + y) ;  heh didn't mean to sound so smug heh sorry!If you assume that these are linear relations (no high order polynomals) (which I think is ok, since it's supposed to be grade 8, and because the answer works out nicely), you can come up with 3 equations:2A + 6B + C = 44A +  B + C = 78A + 3B + C = 1You can solve these to get:f(x,y) = -X - Y + 12(The hard part is knowing how to start these kinds of problems.)    [edited by - mbrown211 on February 2, 2004 9:43:08 AM];quote:Original post by mbrown211  heh didn''t mean to sound so smug heh sorry!If you assume that these are linear relations (no high order polynomals)Which is exactly the kind of information that I was after 