$a) \left (\dfrac{1}{2}+x \right )^2=\dfrac{1}{4}+x+x^2$
$(2x+1)^2=4x^2+4x+1$
$b) (2x+3y)^2=4x^2+12xy+9y^2$
$(0,01+xy)^2=0,0001+0,02xy+x^2y^2$
$c)\left (\dfrac{1}{2}-x \right )^2=\dfrac{1}{4}-x+x^2$
(2x-1)^2=4x^2-4x+1$
$(2x-3y)^2=4x^2-12xy+9y^2$
$(0,01-xy)^2=0,0001-0,02xy+x^2y^2$
$e) (x+1)(x-1)=x^2-1$
$f) (x-2y)(x-2y)=(x-2y)^2=x^2-4xy+4y^2$
$56.64=(60-4)(60+4)=60^2-4^2=3600-16=3584$
$g) (x+y+z)(x-y-z)=[x+(y+z)].[x-(y+z)]$
$=x^2-(y+z)^2$
$=x^2-y^2-2yz-z^2$
$h) (x-y+z)(x+y+z)$
$=(x+z)^2-y^2$
$=x^2+2xz+z^2-y^2$
