To draw a graph on a calculator, we first press the Y= button and type the function in one of the rows. To type a logarithmic function, use the LN button. Having written the function, we can push GRAPH to draw it.
Domain: x>0 Range: All real numbers Asymptote: x=0
Practice makes perfect
We will graph the given function using a graphing calculator. Then, we will determine the domain, range, and asymptote of the function.
y=- log x
Graphing the Function
To draw a graph on a calculator, we first press the Y= button and type the function in one of the rows. To type a logarithmic function, we use the LN button. Having written the function, we can push GRAPH to draw it.
Domain, Range, and Asymptote
Let's recall the function again!
y=- ln x
Note that, considering the real numbers, we can take a logarithm of a positive number only. Therefore, we know that x needs to be greater than 0.
x> 0
From here, we can conclude that the domain of the function is the set of all real numbers greater than 0. Notice that also in the graph, as x approaches 0, the function approaches positive infinity.
Therefore, there is a vertical asymptote at x=0. Since there is no restriction on the values of y, the range is the set of all real numbers.
Domain:& x>0
Range:& All real numbers
Asymptote:& x=0
