3: \(\left(x+3\right)^2+\left(x-2\right)^2-2\left(x+3\right)\left(x-2\right)\)
\(=\left(x+3\right)^2-2\left(x+3\right)\left(x-2\right)+\left(x-2\right)^2\)
\(=\left(x+3-x+2\right)^2\)
\(=5^2=25\)
4: \(\left(3x-5\right)^2-2\left(3x-5\right)\left(3x+5\right)+\left(3x+5\right)^2\)
\(=\left(3x-5-3x-5\right)^2\)
\(=\left(-10\right)^2=100\)