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中學數學...急!!!!

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發問:

(x)(y)=88-------(1) 2x+2y=38-----(2) 求x同y既值

最佳解答:

xy=88---(1) 2x+2y=38---(2) . x+ y=19 . x=19-y---(3) sub (3) into (1) (19-y)y=88 19y-y^2-88=0 y=8 or 11 sub y=8 into (1) . x=11 sub y=11 into (1) . x=8 ANS: y=8,x=11 or y=11,x=8

其他解答:

x y = 88 --------(1) 2x+2y =38 => x+y = 19 -------(2) sub (2) into (1) x(19-x) = 88 x^2 - 19x +88 = 0 (x - 8) (x-11) = 0 x =8 or 11 When y = 11, x =8 or When x = 11, y =8|||||from (2), x=19-y...(3) put(3)into(1), (19-y)y=88 y^2-19y+88=0 y=8 or 11 when y=8,x=11 when y=11,x=8|||||From(1), x=88/y----------(3) Put(3)into(2), 2(88/y)+2y=38 176/y+2y=38 176+2y2=38y y2-19y+88=0 (x-11)(x-8)=0 x=11 or 8
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