计算（1）（3m-4n)(3m+4n)-(2m-2n)(2m+n) (2)(x+5y)²-(x-5y)²快一点～今天必须回答！

（1）（3m-4n)(3m+4n)-(2m-n)(2m+n)
=9m²-16n²-4m²+n²
=5m²-15n²
=5(m-√3n)(m+√3n)
(2)(x+5y)²-(x-5y)²
=(x+5y-x+5y)(x+5y+x-5y)
=20xy

1.=9m^2-16n^2-(4m^2+2mn-4mn-2n^2)
=5m^2-14n^2+2mn
2.=x^2+10xy+25y^2-(x^2-10xy+25y^2)
=20xy

（3m-4n)(3m+4n)-(2m-2n)(2m+n)=9m²-16n²-4m²+2mn+2n²=5m²+2mn-14n²(x+5y)²-(x-5y)²=(x+5y+x-5y)(x+5y-x+5y)=2x*10y=20xy 如果本题有什么不明白可以追问,如果满意请点击“...

（1（3m-4n)(3m+4n)-(2m-2n)(2m+n)
= （3m-4n)(3m+4n)-(2m-2n)(2m+n)
= 9m²-16n² - (4m² -4mn-2n² +2mn)
= 9m²-16n² - 4m²+ 4mn+2n² -2mn
= 5m²-14n² +2mn


(2)(x+5y)²-(x-5y)²
= (x+5y+x-5y) (x+5y-x+5y)
= 2x 10y
= 20 xy