x^-9*x^-2 a 1/x^18b 1/x^11c x^18d x^11
exponent rule : a^-x = 1/a^xx^-9 x^-2 = 1/x^9 1/x^2 = (when multiplying exponents with same base, add exponents)1/x^(9 + 2) =1/x^11
