Answer:
1. [tex]n+m[/tex]
2. [tex]-m+n[/tex]
3. [tex]x^2-y^2[/tex]
4. [tex]a+b[/tex] (no like terms)
5. [tex]a-b[/tex] (no like terms)
Step-by-step explanation:
1. [tex](n+m)[/tex]
[tex]n+m[/tex]
[tex]=m+n[/tex]
2. [tex](n-m)[/tex]
[tex]n-m[/tex]
[tex]=n+-m[/tex]
[tex]=-m+n[/tex]
3. [tex](x - y)(x + y)[/tex]
[tex]=(x+-y)(x+y)[/tex]
[tex]=(x)(x)+(x)(y)+(-y)(x)+(-y)(y)[/tex]
[tex]=x^2+xy-xy-y^2[/tex]
[tex]=x2-y2[/tex]
