1, \(\left(3x-5y\right)^2-2\left(9x^2-25y^2\right)+\left(3x+5y\right)^2\)
\(=\left(3x-5y\right)^2-2\left(3x-5y\right)\left(3x+5y\right)+\left(3x+5y\right)^2\)
\(=\left(3x-5y-3x-5y\right)\)
\(=\left(-10y\right)^2=100y^2\)
2, \(\left(y-3\right)\left(y+3\right)\left(y^2+9\right)-\left(y^2+2\right)\left(y^2-2\right)\)
\(=\left(y^2-9\right)\left(y^2+9\right)-y^4+4\)
\(=y^4-81-y^4+4=-77\)