(2a+3b)^2=(2а)^2+2*2а*3b+(3b)^2=4a^2+12ab+9b^2
(0,1m-2n)^2=(0,1m)^2-2*2n*0,1m+(2n)^2=0,01m^2-0,4mn+4n^2
(-4x+5y)^2=(5y-4x)^2=(5y)^2-2*4x*5y+(4x)^2=25y^2-40xy+16x^2
(-8a-3b)^2= -(-(8a+3b)^2)=(8a+3b)^2= (8a)^2+2*3b*8a+(3b)^2 =64a^2+48ab+9b^2
