2. Today’s Math Answer
0006
( ) (x + y + z)8 xa y b z c ( )( )
a + b + c = 8, a 1, b 1, c 1
a + b + c = 8, a 0, b 0, c 0 ↔ a + b + c = 5, a 0, b 0, c 0
a, b, c a, b, c
8
10! 7!
8+2 C2 = = 45 . . . . . . 5+2 C2 = = 21 . . . . . .
8!2! 5!2!
3. ( ) (x + y + z)8
x = 1, y = 1, z = 1
(1 + 1 + 1)8 = 38
x, y, z x8 , y 8 , z 8
3
x, y, z xa y b (a + b = 8, a
1, b 1) x = 1, y = 1 (1 + 1)8 =
28 x8 , y 8 28 − 2
y b z c , xa z c 3 × (28 − 2)
38 − 3 − 3 × (28 − 2) = 5796 . . . . . .
