#1
a)(3х-1)^2=9х^2-6х+1
б)(2у+3)^3=4у^2+12у+9
в)(х+4у)^2=х^2+8ху+16у^2
г)(0.5m-2n)^2=1/4 m^2-2mn+4n^2
#2
a)(5а+b)^2+(a-5b)^2=25a^2+10ab+b^2+a^2-10ab+25b^2=26a^2+26b^2
b)(3m-2n)^2-(2n+3m)^2=9m^2-12mn+4n^2-25m^2=-16m^2-12mn+4n^2
#3
a)(3x-5)^2=9x^2
9x^2-30x'25=9x^2
-30x=-25
x=5/6
б) (2x+3)^2=4x(2x+3)
4x^2+12x+9=8x^2-12x
4x^2-24x-9=0