Какое равенства верны 1) x^2+y^2-2xy=(x-y) ^2 2) m^2+2mn-n^2=(m-n)^2 3) 49-p^2=(7-p) (7+p) 4) x^2+y^2=(x+y) (x-y) 5)
8+b^3=(2+b) (4-2b+b^2) 6) (x-y)^2=x^2-2xy-y^2