From the above, it can be seen that the nature of polynomial functions is dependent on its degree. Higher the degree of any polynomial function, then higher is its growth. A function which grows faster than a polynomial function is y = f(x) = ax, where a>1. Thus, for any of the positive integers n the function f (x) is said to grow faster than that of fn(x).
Thus, the exponential function having base greater than 1, i.e., a > 1 is defined as y = f(x) = ax. The domain of exponential function will be the set of entire real numbers R and the range are said to be the set of all the positive real numbers.
It must be noted that exponential function is increasing and the point (0, 1) always lies on the graph of an exponential function. Also, it is very close to zero if the value of x is mostly negative.
Exponential function having base 10 is known as a common exponential function. Consider the following series:
Derivative of logarithmic and exponential function 5
The value of this series lies between 2 & 3. It is represented by e. Keeping e as base the function, we get y = ex, which is a very important function in mathematics known as a natural exponential function.
For a > 1, the logarithm of b to base a is x if ax = b. Thus, loga b = x if ax = b. This function is known as logarithmic function.
Derivative of logarithmic and exponential function 2
For base a = 10, this function is known as common logarithm and for the base a = e, it is known as natural logarithm denoted by ln x. Following are some of the important observations regarding logarithmic functions which have a base a>1.
The domain of log function consists of positive real numbers only, as we cannot interpret the meaning of log functions for negative values.
For the log function, though the domain is only the set of positive real numbers, the range is set of all real values, i.e. R
When we plot the graph of log functions and move from left to right, the functions show increasing behaviour.
The graph of log function never cuts x-axis or y-axis, though it seems to tend towards them.
Derivative of logarithmic and exponential function 3
Logap = α, logbp = β and logba = µ, then aα = p, bβ = p and bµ = a
Logbpq = Logbp + Logbq
Logbpy = ylogbp
Logb (p/q) = logbp – logbq
Exponential Function Derivative
Let us now focus on the derivative of exponential functions.
The derivative of ex with respect to x is ex, i.e. d(ex)/dx = ex
It is noted that the exponential function f(x) =ex has a special property. It means that the derivative of the function is the function itself.
(i.e) f ‘(x) = ex = f(x)
Exponential Series
Exponential Functions
Exponential Function Properties
The exponential graph of a function represents the exponential function properties.
Let us consider the exponential function, y=2x
The graph of function y=2x is shown below. First, the property of the exponential function graph when the base is greater than 1.
Exponential Functions
Exponential Function Graph for y=2x
The graph passes through the point (0,1).
The domain is all real numbers
The range is y>0
The graph is increasing
The graph is asymptotic to the x-axis as x approaches negative infinity
The graph increases without bound as x approaches positive infinity
The graph is continuous
The graph is smooth
Exponential Functions
Exponential Function Graph y=2-x
The graph of function y=2-x is shown above. The properties of the exponential function and its graph when the base is between 0 and 1 are given.
The line passes through the point (0,1)
The domain includes all real numbers
The range is of y>0
It forms a decreasing graph
The line in the graph above is asymptotic to the x-axis as x approaches positive infinity
The line increases without bound as x approaches negative infinity
It is a continuous graph
It forms a smooth graph
Exponential Function Rules
Some important exponential rules are given below:
If a>0, and b>0, the following hold true for all the real numbers x and y:
ax ay = ax+y
ax/ay = ax-y
(ax)y = axy
axbx=(ab)x
(a/b)x= ax/bx
a0=1
a-x= 1/ ax
Exponential Functions Examples
The examples of exponential functions are:
f(x) = 2x
f(x) = 1/ 2x = 2-x
f(x) = 2x+3
f(x) = 0.5x
Solved problem
Question:
Simplify the exponential equation 2x-2x+1
Solution:
Given exponential equation: 2x-2x+1
By using the property: ax ay = ax+y
Hence, 2x+1 can be written as 2x. 2
Thus the given equation is written as:
2x-2x+1 =2x-2x. 2
Now, factor out the term 2x
2x-2x+1 =2x-2x. 2 = 2x(1-2)
2x-2x+1 = 2x(-1)
2x-2x+1 = – 2x