😃15.4 無窮級數

https://www.geogebra.org/m/j6QR8z3j

例1 https://www.geogebra.org/m/ec8utxsm

例1 https://www.geogebra.org/m/RMCa8Fej

例2 https://www.geogebra.org/m/y3UycAtX