What is the value of this expression when a = 3 and b = -2?

The first step: Simplify the expression with:
[tex]\dfrac{x^n}{x^m}=x^{n-m}\\\\(xy)^n=x^ny^n\\\\(x^n)^m=x^{nm}\\\\x^{-n}=\dfrac{1}{x^n}[/tex]
[tex]\left(\dfrac{3a^{-2}b^6}{2a^{-1}b^5}\right)^2=\left(\dfrac{3}{2}a^{-2-(-1)}b^{6-5}\right)^2=\left(\dfrac{3}{2}a^{-1}b^1\right)^2\\\\=\left(\dfrac{3}{2}\right)^2(a^{-1})^2b^2=\dfrac{9}{4}a^{-2}b^2=\dfrac{9b^2}{4a^2}[/tex]
The second step: Put the values of a = 3 and b = -2 to the expression:
[tex]\dfrac{9(-2)^2}{4(3)^2}=\dfrac{(9)(4)}{(4)(9)}=1[/tex]