Question

(х+у)2-(х-у)2=?
(2m-n)2-(m+2n)2=?
(3n+2p)2-(5p-2n)

Answer 1

Используем формулы сокращенного умножения и раскрываем скобки, затем приводим подобные
1)  (х+у)^2-(x-y)^2=x^2+2xy+y^2-(x^2-2xy+y^2)=x^2+2xy+y^2-x^2+2xy-y^2=4xy
2) (2m-n)^2-(m+2n)^2=4m^2-4mn+n^2-(m^2+4mn+4n^2)=4m^2-4mn+n^2-m^2-4mn-4n^2=3m^2-8mn-3n^2
3)(3n+2p)^2-(5p-2n)^2=9n^2+12np+4p^2-25p^2+20pn-4n^2=5n^2+32np-21p^2

Answer 2

$(x+y)^2-(x-y)^2=x^2+2xy+y^2-x^2+2xy-y^2=4xy$

$(2m-n)^2-(m+2n)^2=4m^2-4mn+n^2-m^2-4mn-4n^4=$$4m^2-4mn+n^2-m^2-4mn-4n^4=3m^2-8mn-3n^2$

$(3n+2p)^2-(5p-2n)^2=9n^2+12np+4p^2-25p^2+20pn-4n^2=$$9n^2+12np+4p^2-25p^2+20pn-4n^2=5n^2+32np-21p^2$