唔識做功課8

b = (4x + 3y)/(2x - y)
(2x - y)b = 4x + 3y
2bx - by = 4x + 3y
3y + by = 2bx - 4x
y(3 + b) = x(2b - 4)
y = x(2b - 4) / (3 + b)

- - - - -
但你的答案是
y = x(2b - 4) / (3 - b)

由答案推上去問題的話:
y = x(2b - 4) / (3 - b)
(3 - b)y = x(2b - 4)
3y - by = 2xb - 4x
4x + 3y = 2xb + by
4x + 3y = b(2x + y)
b = (4x + y)/(2x + y)

…要麼問題 裡 (2x - y) 裡的正負數錯了
要麼,就是你答案裡 (3 - b) 裡的正負數錯了

b=4x+3y/2x-y
b(2x-y)=4x+3y
2bx-by=4x+3y
-by-3y=4x-2bx
-y(b+3)=2x(2-b)
-y=2x(2-b)/(b+3)
y=-2x(2-b)/(b+3)





額外問題:你有玩忍3嗎?