数学题．．．．．．

1.x^(m+n)除以x^n=x^3
得：m=3

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

=[a+(b-c)][a-(b-c)]

=a^2-(b-c)(b-c)

=a^2-b^2+2bc-c^2

3
a^2-b^2+2bc-c^2

1.x^(m+n)/x^n
=x^(m+n-n)
=x^m
=x^3
m=3

2.(a+b-c)*(a-b+c)
=[a+(b-c)][a-(b-c)]
=a^2-(b-c)^2
=a^2-b^2+2bc-c^2

(1)x^m+n/x^n=x^3
x^(m+n-n)=x^3
m=2
(2)(a+b-c)*(a-b+c)
=[a+(b-c)]*[a-(b-c)]
=a^2-(b-c)^2
=a^2-b^2+2bc-c^2

1.x^m+n-n=x^3
m=3同底数幂相除，底数不变指数相减。
2.（a-(c-b)）*(a+(c-b))=a^2-(c-b)^2