1. Simultaneous Equation
Casio fx-570MS: https://www.youtube.com/watch?v=CC0WiH82tJs
Casio fx-570ES: https://www.youtube.com/watch?v=9EUf3fWp2TY
Casio fx-570EX (maybe): https://www.youtube.com/watch?v=FbDysTAuSjc
2. Complex Number
Casio fx-570MS: https://www.youtube.com/watch?v=rGhlFl_W_XY
Casio fx-570ES (maybe): https://www.youtube.com/watch?v=_BzVUGQf33M
Casio fx-570EX (maybe): https://www.youtube.com/watch?v=atr9iGyCboY