唔識做功課9 @ lgzrelv的部落格

標題:

唔識做功課8

發問:

Make y the subject of the formula 2X一y分之4X+3y b= 4x+3y / 2x-y 更新: 1.no,2.但答案係y=3-b分之x(2b-4)

最佳解答:

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

其他解答:

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?