public override Expr Diff() => !IsConstant?Operand1.Diff() *Operand2 + Operand2.Diff() *Operand1 : new Constant(0);
public override Expr Diff() => !IsConstant ? (Operand1.Diff() * Operand2 - Operand2.Diff() * Operand1) / Pow(Operand2, 2) : new Constant(0);