x2+y2=25 , 3x-4y=0. 求解答?
回答 (9)
2016-01-08 8:21 am
✔ 最佳答案
(4,3).(-4,-3) 
2016-01-06 11:28 pm
Sol
3x－4y=0
3x=4y
x^2+y^2=25
9x^2+9y^2=225
16y^2+9y^2=225
25y^2=225
y^2=9
y=+/-3
(1) y=3
3x=12
x=4
(x，y)=(4，3)…………………..
(2) y=－3
3x=－12
x=－4
(x，y)=(－4，－3)……………..
3x－4y=0
3x=4y
x^2+y^2=25
9x^2+9y^2=225
16y^2+9y^2=225
25y^2=225
y^2=9
y=+/-3
(1) y=3
3x=12
x=4
(x，y)=(4，3)…………………..
(2) y=－3
3x=－12
x=－4
(x，y)=(－4，－3)……………..
2016-01-07 3:16 pm
X=4
Y=3
Y=3
2016-01-19 1:08 pm
x = 4 , y = 3 or x = -4 , y = -3
2016-01-11 3:24 pm
偷懶喔~
2016-02-02 1:32 pm
令
x = 5cos(A) , y = 5sin(A)
因為 3(5cos(A)) - 4(5sin(A)) = 0
所以 tan(A) = 3/4
所以 cos(A) = 4/5 , sin(A) = 3/5 或
cos(A) = - 4/5 , sin(A) = - 3/5
所以 x = 4 , y = 3 或
x = -4 , y = -3
x = 5cos(A) , y = 5sin(A)
因為 3(5cos(A)) - 4(5sin(A)) = 0
所以 tan(A) = 3/4
所以 cos(A) = 4/5 , sin(A) = 3/5 或
cos(A) = - 4/5 , sin(A) = - 3/5
所以 x = 4 , y = 3 或
x = -4 , y = -3
2016-01-20 8:39 am
哈哈，说答案有-4，-3的，都上当了吧！！！
2016-01-07 3:06 am
x=4,y=3 &x=-4 y=-3
2016-01-06 3:37 pm
第二式的y以x表示並帶入第一式
收錄日期: 2021-04-18 14:22:15
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