Of course you can use the quotient rule, but it is usually not the easiest method. If we do use it here, we get $${d\over dx}{10\over x^2}={x^2\cdot 0-10\cdot 2x\over x^4}= {-20\over x^3},$$ since the derivative of 10 is 0.
1 Young children can't tell the difference between fantasy and reality. 2  Your preschooler's rich imagination is a big part of his normal development, but that means it is usually hard for him to tell the difference between what's real and what's imaginary.
Fantasy is a popular genre, having found a home for itself in almost every medium. While fantasy art and recently fantasy films have been increasingly popular, it is fantasy literature which has always been the genre's primary medium. Fantasy role-playing games cross several different media.