[問題]GWD 12 -- 27,34

[hippo3333]

12.

A box contains exactly 24 balls, of whick 12 are red and 12 are blue. If two balls are to be picked from this box at random and without replacement, what is the probaility that both balls will be red?

A 11/46

34.

If 2X^2-y^2=2XY, then (X+Y)^2 =?

B 3X^2

拜託大大了

[FrankChang]

34.(X+Y)^2=X^2+Y^2+2XY
=X^2+Y^2+2X^2-Y^2
=3X^2

[chour]

12.

C(12,2)/C(24,2)=11/46

[hippo3333]

謝謝 原來我的問題這樣簡單