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!
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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!
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!
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!
(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
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(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
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
(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