數學功課.......

1. (X[2]-3X[3]+2)+(X[4]+3X[2]-1)
= 2X - 9X + 2 + 4X + 6X -1
= 3X -1

2. 4(a[2]+2a-3)-(2a[2]-12-a)
= 8a + 8a -12 - 4a + 24+ a
= 13a +12

3. (3X[3]-4X[2]+8-5X)+2(X[3]-2X+X[2]-6)
= 9X - 8X +8 - 5X + 6X - 4X + 4X - 12
= 2X -4

4. 1/2(-3y[2]+y-3)-1/2(5y[2]-1-3y)-2(4-y[2]+3y)
= -3y + y -3 - 5y +1 +3y -8 + 4y - 6y
= -7y -10

---[*]係指幾次方...>.<

(X[2]-3X[3]+2)+(X[4]+3X[2]-1)
=X[2]-3X[3]+2+X[4]+3X[2]-1
=X[4]-3X[3]+4X[2]+1

4(a[2]+2a-3)-(2a[2]-12-a)
=4a[2]+8a-12-2a[2]+12+a
=2a[2]+9a

(3X[3]-4X[2]+8-5X)+2(X[3]-2X+X[2]-6)
=3X[3]-4X[2]+8-5X+2X[3]-4X+2X[2]-12
=5X[3]-2X[2]-9X-4

1/2(-3y[2]+y-3)-1/2(5y[2]-1-3y)-2(4-y[2]+3y)
=-3/2y[2]+1/2y-3/2-5/2y[2]+1/2+3/2y-8+2y[2]-6y
=-2y[2]-4y-9

2007-08-21 21:56:59 補充：
下次可以用 ''^2'' 代表指數！