Thursday, November 3, 2011

10-31 Class notes - Restricted domains

When listing or describing the domain of a function, see if you have to exclude any x's because of these rules regarding real numbers:

Division by zero is undefined.

The square root of a negative number is not defined.

If an x appears in a denominator or underneath a square root sign,  set that expression equal to zero and solve for x to see which x's should be excluded from the domain. Describe the domain as real numbers with some x's excluded or omitted.


When listing or describing the raange of a function, see how far the graph goes along the y-axis.  For example, functions containing an x-squared term have a curved part that changes direction so that some y's never appear on the graph.  Describe the range as an inquality in y.

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