(х+2у)^2=x^2+4xy+4y^2, (x+5)^2=x^2+10x+25, 2)(7-a)^2=49-14a+a^2, (x-3y)^2=x^2-6xy+9y^2, 3) x^2-4y^2=(x-2y)(x+2y), (x^2-1)=(x-1)(x+1), 4) (2x-3)(2x+3)=4x^2-9, (ab-c)(ab+c)=a^2b^2-c^2, 5) a^3-8=(a-2)(a^2+2a+4), b^3-27=(b-3)(b^2+3b+9), 6)x^3+y^3=(x+y)(x^2-xy+y^2), 7)(a-1)^3=a^3-3a^2+3a+1, (2-x)^3=4-12x+6x^2+x^3, 8) (x+1)^3=x^3+3x^2+3x+1, (2+y)^3=8+12y+6y^2+y^3