let 紅波ge數目係x 藍波ge數目係y P(2red)=x/(x+y)*(x-1)/(x+y-1) P(2blue)=y/(x+y)*(y-1)/(x+y-1) 兩個紅色球的機率是抽出兩個藍色球機率的5倍
SO,x/(x+y)*(x-1)/(x+y-1)=5y/(x+y)*(y-1)/(x+y-1)
x(x-1)=5y(y-1)-----------1
P(1red,1blue)=x/(x+y)*y/(x+y-1)+y/(x+y)*x/(x+y-1) 出一個紅色球和一個藍球的機率是抽出兩個藍色球機率的6倍
SO,x/(x+y)*y/(x+y-1)+y/(x+y)*x/(x+y-1)=6y/(x+y)*(y-1)/(x+y-1)
2xy=6y(y-1)
x=3y-3-----------------2
Put 2 into 1
(3y-3)(3y-3-1)=5y(y-1)
9y^2-21y+12=5y^2-5y
4y^2-16y+12=0
y^2-4y+3=0
y=3 or 1
From 2 put y=1 put y=3
x=3y-3 x=3y-x
x=3(1)-3 x=3(3)-3
x=0(reject) x=6
所以 紅波有6粒 藍波有3粒 岩ma???
還有戰俘大果題真係唔識答- -