1. a) (3x+x)^2=9x^2+6x^2+x^2=16x^2
или (3х+х)^2=(4x)^2=16x^2
б) (4х-1)^2=16x^2-8x+1
в) (2x+3y)^2=4x^2+12xy+9y^2
г) (x^2-5)^2=x^4-10x^2+25
2. a) x^2+4x+4=(x+2)^2
б) 25x^2-10xy+y^2=(5x-y)^2
3. a) (7x-2)^2+28x=49x^2-28x+4+28x=49x^2+4
б) 32y-2(1+8y)^2=32y-2-32y-128y^2=128y^2-2