u = log, x find in terms of u: 1) x = by the definition of logarithms (or writing in exponential form). 2) log, (3x) = Using the property loga (MN) = loga M + loga N = + u By simplifying and substitution. 3) Let log, 81 = y. Then by rewriting this equation as an exponential we obtain, 81 = By substituting our value of x found earlier, 81 = (94). This we can rewrite so both sides have the same base to obtain 92 = 9"y. By equating exponents we get the equation: which is then solved for y, y = Thus log, 81 =