Simplify the following expressions using the perfect square formulas:

Here, $a=x$ and $b=3$.

$$(x+3)^2 = x^2 + 2(x)(3) + 3^2$$

$$= x^2 + 6x + 9$$

The simplified expression is $\boxed{x^2 + 6x + 9}$.

Here, $a=x$ and $b=3$.

$$(x-3)^2 = x^2 - 2(x)(3) + 3^2$$

$$= x^2 - 6x + 9$$

The simplified expression is $\boxed{x^2 - 6x + 9}$.

Here, $a=x$ and $b=7$.

$$(x+7)^2 = x^2 + 2(x)(7) + 7^2$$

$$= x^2 + 14x + 49$$

The simplified expression is $\boxed{x^2 + 14x + 49}$.

Here, $a=x$ and $b=1$.

$$(x-1)^2 = x^2 - 2(x)(1) + 1^2$$

$$= x^2 - 2x + 1$$

The simplified expression is $\boxed{x^2 - 2x + 1}$.

Here, $a=x$ and $b=12$.

$$(x-12)^2 = x^2 - 2(x)(12) + 12^2$$

$$= x^2 - 24x + 144$$

The simplified expression is $\boxed{x^2 - 24x + 144}$.

Here, $a=x$ and $b=9$.

$$(x-9)^2 = x^2 - 2(x)(9) + 9^2$$

$$= x^2 - 18x + 81$$

The simplified expression is $\boxed{x^2 - 18x + 81}$.

Here, $a=x$ and $b=11$.

$$(x+11)^2 = x^2 + 2(x)(11) + 11^2$$

$$= x^2 + 22x + 121$$

The simplified expression is $\boxed{x^2 + 22x + 121}$.

Here, $a=2x$ and $b=1$.

$$(2x-1)^2 = (2x)^2 - 2(2x)(1) + 1^2$$

$$= 4x^2 - 4x + 1$$

The simplified expression is $\boxed{4x^2 - 4x + 1}$.

Here, $a=3x^3$ and $b=2y^2$.

$$(3x^3 - 2y^2)^2 = (3x^3)^2 - 2(3x^3)(2y^2) + (2y^2)^2$$

$$= 9x^6 - 12x^3y^2 + 4y^4$$

The simplified expression is $\boxed{9x^6 - 12x^3y^2 + 4y^4}$.

j)

Here, $a=9x^2$ and $b=m^8$.

$$(9x^2 - m^8)^2 = (9x^2)^2 - 2(9x^2)(m^8) + (m^8)^2$$

$$= 81x^4 - 18x^2m^8 + m^{16}$$

The simplified expression is $\boxed{81x^4 - 18x^2m^8 + m^{16}}$.

k)

Here, $a=2p$ and $b=q^2$.

$$(2p-q^2)^2 = (2p)^2 - 2(2p)(q^2) + (q^2)^2$$

$$= 4p^2 - 4pq^2 + q^4$$

The simplified expression is $\boxed{4p^2 - 4pq^2 + q^4}$.