1..题目是不是给错了,应该是3x³吧?
n+3=0 n=-3
5-m=0 m=5
2.【(m+n)(m-n)-(m-n)²+2n(m-n)】÷4n
=【m²-n²-m²-n²+2mn+2mn-2n²】/4n
=【4mn-4n²】/4n
=m-n
=5+3=8
1..题目是不是给错了,应该是3x³吧?
n+3=0 n=-3
5-m=0 m=5
2.【(m+n)(m-n)-(m-n)²+2n(m-n)】÷4n
=【m²-n²-m²-n²+2mn+2mn-2n²】/4n
=【4mn-4n²】/4n
=m-n
=5+3=8