$a){\left(x+1\right)}^2=x^2+2\cdot 1\cdot x+1^2=x^2+2x+1$

$b){\left(x+3\right)}^2=x^2+2\cdot x\cdot 3+3^2=x^2+6x+9$

$c){\left(a+5\right)}^2=a^2+2\cdot a\cdot 5+5^2=a^2+10a+25$

$d){\left(2a+1\right)}^2={\left(2a\right)}^2+2\cdot 2a\cdot 1+1^2=4a^2+4a+1$

$e){\left(2b+2\right)}^2={\left(2b\right)}^2+2\cdot 2b\cdot 2+2^2=4b^2+8b+4$

$f){\left(3b+2\right)}^2={\left(3b\right)}^2+2\cdot 2\cdot 3b+2^2=9b^2+12b+4$

$g){\left(3y+\frac{1}{2}\right)}^2={\left(3y\right)}^2+{\sout{2}}^1\cdot 3y\cdot \frac{1}{{\sout{2}}^1}+{\left(\frac{1}{2}\right)}^2=9y^2+3y+\frac{1}{4}$

$h){\left(\frac{1}{4}y+2\right)}^2={\left(\frac{1}{4}y\right)}^2+2\cdot \frac{1}{4}y\cdot 2+2^2=\frac{1}{16}{y}^2+\frac{4}{4}y+4=\frac{1}{16}{y}^2+y+4$