一個短跑手,順風跑90米,用了10秒,狂同樣的風速下,逆風跑了70米也用了10秒.那麼在無風的時侯跑一百米,需時幾秒? |
13 1/3秒 |
請列式 |
好想打你] let x be the speed of the athlete y be the speed of wind x+y=90m/10s...........1 x-y=70m/10s............2 1+2 2x=15 x=7.5 ∴the speed of athlete is 7.5m/s ∴the second the athlete use when windless is 100/7.5=13 1/3 |
我又要打!!! |
打你個頭. |
你真係問左^_^ |
係.. miss話係12.5s... |
.......... 唔知答你咩好+3+ 因為我對maths真係無D認識-_- |
你該答我...哦"//係咩? |
嗯^_^ 知道了*v* |
這就對了. |
打你果個呀!!你個大dd |
你個大dd<<<?? |
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