Current location - Training Enrollment Network - Mathematics courses - High school mathematics arrangement and combination, five different balls in three boxes, two questions, one, what's wrong with the method in mathematics? Find out the mistakes, and secondly, I
High school mathematics arrangement and combination, five different balls in three boxes, two questions, one, what's wrong with the method in mathematics? Find out the mistakes, and secondly, I
Sister answers your first question first, the formula is correct, and the calculation in the second step is wrong. C53= 10 times A33 equals 60.

The second question is (C53 * A33 * 3)/3+(C53 * A33 * 6)/A22 * A22. Description: c53 a33 is a 5-ball box, which is used to select and place three balls. The first persimmon multiplied by three means that there are two balls left in a box (that is, 3 1 1). There are three situations, and dividing by three indicates the order (for example, abc is in the box, de indicates the ball is in the box A, and dbc indicates AE; Ebc is the same as ad. Or it can be c2 1 times 3, which means that two balls are placed in order. Choose three boxes and divide them directly by A33, which is normal, but I wrote simplification above). The second persimmon is the same. You can ask if you don't understand.