Convert the 81 to 3y, where y is the power that will produce 81 81=3×3×3×3 From the law of indices, ab×ac=ab+c 81=3×3×3×3=31+1+1+1=34 Now replace 81 by 34 in the equation 3x=81 3x=34 Since the bases are the same, the powers are also the same Hence x=4