1.設X.Y均為分數,若
(x+5y- 6)二次方+(3x- 6y-4)二次方=0
求X和Y之值。
2. 123x+77y=261.......(1)
77x+123y=-61........(2)
3.設
3x- 4y=13
2ax-5by=41
與
2x+5y=-11
3ax-4by=30有相同的解,求a和b?
4. 解: 41x+19y=158......(1)
49x+15y=158......(2)
5. 解 2x-1/3(3是分母)=y+1/2=x+y+1/4
2006-02-08 18:54:04 · 5 個解答 · 發問者 美伶 1 in 科學 ➔ 數學
設X.Y均為分數,若(x+5y- 6)二次方+(3x- 6y-4)二次方=0,求X和Y之值。解: x + 5y - 6 = 0 --------- (1) 3x - 6y - 4 = 0 --------- (2) 由 (1)x3-(2) 得 21y - 14 = 0 y = 2/3 x = 8/3 123x+77y=261.......(1)77x+123y=-61........(2)解:(1)+(2) 200x + 200y = 200 x + y = 1 -------- (3) (1)-(2) 46x - 46y = 322 x - y = 7 -------- (4) (3)+(4) 2x = 8 x = 4 y = -3設3x- 4y=132ax-5by=41 與2x+5y=-113ax-4by=30有相同的解,求a和b?解: 3x - 4y = 13 --------- (1) 2x + 5y = -11 --------- (2) (1)x5+(2)x4 得 23x = 21 x = 21/23 y = -59/23 代入 2ax-5by=41 3ax-4by=30 得 42a/23 + 295b/23 = 41 ------ (3) 63a/23 + 236b/23 = 30 ------ (4) (3)x3-(4)x2 得 b = 1449/413 a = -46/21 41x+19y=158......(1)49x+15y=158......(2)解:(2)-(1) 8x - 4y = 0 2x = y (1)+(2) 90x + 34y = 316 45y + 34y = 316 y = 4 x = 22x-1/3(3是分母)=y+1/2=x+y+1/4 解:因題意不太清楚,所以有兩種解法: 一、 (2x-1)/3=(y+1)/2=(x+y+1)/4 得 2(2x-1) = 3(y+1) ------ (1) 及 2(y+1) = x+y+1 ------ (2) 由 (1) 4x-2 = 3y+3 得 4x - 3y = 5 ----------- (3) 由 (2) 2y+2 = x+y+1 得 x - y = 1 ------------- (4) (3)-(4)x3 x = 2 y = 1 二、2x - 1/3 = y + 1/2 = x + y + 1/4 得 2x - y = 1/2 + 1/3 = 5/6 及 x = 1/4 故 y = -1/3
2006-02-09 09:17:44 補充:
第三題補充: b = 1449/413 = (23x7x9)/(59x7) = 207/59 (忘了約分)
2006-02-08 20:10:11 · answer #1 · answered by Frank 7 · 0⤊ 0⤋
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2014-06-30 22:55:52 · answer #2 · answered by Anonymous · 0⤊ 0⤋
1. 因為平方是正的所以0+0=0
因此 X+5Y-6=0 , 3X-6Y-4=0
解兩聯立得X=8/3. Y=2/3 #
2. 解兩聯立可得X=4. Y=-3 #
3. 有相同解就是:兩聯立的X.Y解會一樣
SO就可把3x- 4y=13 , 2x+5y=-11
解聯立得X=21/23 Y=-59/23 再帶入2ax-5by=41 3ax-4by=30
求得 a=-46/21 b=207/59 #
4. 解兩聯立可得x=2 .y=4 #
5. 可以分成2x-1/3=y+1/2 y+1/2=x+y+1/4
經交叉相乘可得兩聯立方程式
解聯立可得x=1/4 y=-1/3 #
2006-02-08 20:26:27 · answer #3 · answered by Elva's Choice~💋 2 · 0⤊ 0⤋
(1) x=8/3,y=2/3
(2)x=4,y=-3
(3)x=21/23,y=-59/23 所以a=-46/21,b=207/59
(4)x=2,y=4
(5)x=1/4,y=-1/3
2006-02-08 19:44:33 · answer #4 · answered by 玉米 2 · 0⤊ 0⤋
1. x=8/3 (3是分母) y=2/3 (3是分母)
2. x= 4 y=-3
3. ??
4. ??
5. x=1/4 (4是分母) y=-1/3(3是分母)
慚愧~不會算=.=
2006-02-08 19:43:21 · answer #5 · answered by JOSH 3 · 0⤊ 0⤋