median
don steward
mathematics teaching 10 ~ 16

Tuesday, 25 January 2011

simultaneous equations with patterns

based on the Moscow Puzzles (originally published in 1956) by Boris Kordemsky
number 240 (is question number 6 below)

looking carefully at the coefficients...
what do you notice?
how does it help?

















what happens if you add the two equations?
what happens if you subtract them?


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