有數學唔識做？？

1. a+2b+a-3b-c
a+a+2b-3b-c
2a-b-c

2. 3x+y-2x+2y+3z
3x-2x+y+2y+3z
x+3y+3z

3. 6p+4q-5q+4r
6p-q+4r

4. 5x+7y-8x+6y+3z
5x-8x+7y+6y+3z
-3x+13y+3z
3x-13y-3z

1.(a+2b)+(a-3b-c)
=a+2b+a-3b-c
=2a-b-c

2.(3x+y)-(2x-2y-3z)
=3x+y-2x+2y+3z
=x+3y+3z

3.(6p+4q)_(5q-4r)
=6p+4q-5q+4r
=6p-q+4r

4.(5x+7y-(8x-6y-3z)
=5x+7y-8x+6y+3z
=-3x+13y+3z

1.(a+2b)+(a-3b-c)
=a+2b+a-3b-c
=2a-b-c//

2.(3x+y)-(2x-2y-3z)
=3x+y-2x+2y+3z
=x+3y+3z//

3.(6p+4q)-(5q-4r)
=6p+4q-5q+4r
=6p-q+4r//

4.(5x+7y-(8x-6y-3z)
=5x+7y-8x+6y+3z
=-3x+13y+3z//

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1.(a+2b)+(a-3b-c)

=a+2b+a-3b-c

=2a-b-c


2.(3x+y)-(2x-2y-3z)

=3x+y-2x+2y+3z

=x+3y+3z


3.(6p+4q)-(5q-4r)

=6p+4q-5q+4r

=10r-q


4.(5x+7y)-(8x-6y-3z)

=5x+7y-8x+6y+3z

= -3x+13y+3z

2007-05-28 23:13:03 補充：
sor....3.(6p 4q)-(5q-4r)=6p 4q-5q 4r=6p-q 4r

2007-05-28 23:13:39 補充：
me