If x,y,and k are positive numbers such that [X/(X+Y)]*10+[Y/(X+Y)]*20=k,and if x < y,which of the following could be the value of A.10B.12C.15D.18E.30
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![If x,y,and k are positive numbers such that [X/(X+Y)]*10+[Y/(X+Y)]*20=k,and if x < y,which of the following could be the value of A.10B.12C.15D.18E.30](/uploads/image/z/10144920-48-0.jpg?t=If+x%2Cy%2Cand+k+are+positive+numbers+such+that+%5BX%2F%28X%2BY%29%5D%2A10%2B%5BY%2F%28X%2BY%29%5D%2A20%3Dk%2Cand+if+x+%3C+y%2Cwhich+of+the+following+could+be+the+value+of+A.10B.12C.15D.18E.30)
If x,y,and k are positive numbers such that [X/(X+Y)]*10+[Y/(X+Y)]*20=k,and if x < y,which of the following could be the value of A.10B.12C.15D.18E.30
If x,y,and k are positive numbers such that [X/(X+Y)]*10+[Y/(X+Y)]*20=k,and if x < y,which of the following could be the value of
A.10
B.12
C.15
D.18
E.30
If x,y,and k are positive numbers such that [X/(X+Y)]*10+[Y/(X+Y)]*20=k,and if x < y,which of the following could be the value of A.10B.12C.15D.18E.30
式子左边=[10+10y/(x+y)]
因为x(10+5)=15
只有D、E待选
又因为positive number,你把E代回去试一下:2x+y=0,肯定是一正一负
所以选D
自己想的,不知道对不对~~