`1)`

`A=3/4x^(n-1)·4/5x^(2n-1)y^(2n+1)·5/6xy^(n+1)`

`A=(3/4·4/5·5/6)·(x^(n-1)·x^(2n+1)·x)·(y^(2n+1)·y^(n+1))`

`A=1/2x^(n-1+2n+1+1)y^(2n+1+n+1)`

`A=1/2x^(3n+1)y^(3n+2)`

Hệ số: `1/2`

Bậc: `3n+1+3n+2=6n+3`

`2)`

`B=6/4x^(3-n)·4/2x^(4-n)y^(5-n)·2/6y^(6-n)`

`B=(6/4·4/2·2/6)·(x^(3-n)·x^(4-n))·(y^(5-n)·y^(6-n))`

`B=x^(3-n+4-n)y^(5-n+6-n)`

`B=x^(7-2n)y^(11-2n)`

Hệ số: `1`

Bậc: `7-2n+11-2n=18-4n`

`3)`

`C=-4/3x^(2-n)y·6/7x^(2n-3)y^(n-1)·(-1)/2xy`

`C=[-4/3·6/7·(-1/2)]·(x^(2-n)·x^(2n-3)·x)·(y·y^(n-1)·y)`

`C=4/7x^(2-n+2n-3+1)y^(1+n-1+1)`

`C=4/7x^ny^(n+1)`

Hệ số: `4/7`

Bậc: `n+n+1=2n+1`

`4)`

`D=1/5xy^(n+1)·4/3x^(n+1)y·15/7x^ny^n`

`D=(1/5·4/3·15/7)·(x·x^(n+1)·x^n)·(y^(n+1)·y·y^n)`

`D=4/7x^(1+n+1+n)y^(n+1+1+n)`

`D=4/7x^(2n+2)y^(2n+2)`

Hệ số: `4/7`

Bậc: `2n+2+2n+2=4n+4`