When solving the problem, try to turn it into a logarithmic function that unit results are transformed into each other: y=lnx exponential function: y = e.

X exponential function: it is an important function in mathematics. This function applied to the value e is written as exp( x). It can also be written as ex, where e is a mathematical constant and the base of natural logarithm, which is about equal to 2.7 1828 1828, also known as Euler number. Exponential function: in general, if ax = n(a >；; 0, and a≠ 1), then the number x is called the logarithm of the base of n, denoted as x= log aN, and read as the logarithm of the base of n, where a is called the base of logarithm and n is called a real number. Function y = logax(a & gt；; 0, and a≠ 1) is called logarithmic function, that is, a function with power (real number) as independent variable, exponent as dependent variable and base constant as constant is called logarithmic function.