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Maths 一問 Quick
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Simultaneous Equcations:1)By selling 5 pigs and buying 2 cows, Thomas increase his cash bu $8000. If he sells 9 pigs and buys 4 cows, he will increase his cash by $10000, find rhe piece of (a) a pig (b) a cowLinear Inequalities:1) The length of a... 顯示更多 Simultaneous Equcations: 1)By selling 5 pigs and buying 2 cows, Thomas increase his cash bu $8000. If he sells 9 pigs and buys 4 cows, he will increase his cash by $10000, find rhe piece of (a) a pig (b) a cow Linear Inequalities: 1) The length of a rectangle is twice its width and its perimeter is at most 48 cm. Find the greatest possible dimensions of the rectangle.
最佳解答:
1) Let p be the price of a pig c be the price of a cow 5p - 2c = 8000 -----------(1) 9p -4c = 10000 -----------(2) (1)X2 10p - 4c = 16000 ----------(3) (3)-(2) p = 6000----(4) Sub (4) into (1) 5(6000) - 2c = 8000 c = 11000 2) Let l be the length w be the width l = 2w --------(1) 2(l+w) = 48 -----------(2) sub (1) into (2) 2(2w+w) = 48 6w =48 w = 8-----(3) Sub (3) into 1 l = 2(8) l = 16 so the dimension is 16 X 8
其他解答:
1) Assume the price of a pig is $X, and that of a cow is $Y. 5X-2Y=8000 and 9X-4Y=10000 X=(10000+4Y)/9 5X-2Y=8000 50000/9+4/9Y-2Y=8000 5/9(10000+4Y)-2Y=8000 50000+20Y-18Y=72000 2Y=22000 Y=11000 5X-2Y=8000 5X-2(11000)=8000 5X-22000=8000 5X=30000 X=6000 i.e.: A pig costs $6000 while a cow costs $11000 (I have to say that I'm not really sure about the 2nd Qs.) 2) Assume the Length of the rectangle is Lcm while the width of it is Wcm. L=2W and 2L+2W
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