Please Help

[ladyhawk0965]

Hi,

I'm looking for information on the similarities and differences between operations on numeric fractions and operations involving rational expressions. Also can you explain how to find the reciprocal of an expression.

Thanks so much,

Ladyhawk0965

 

[stapel]

I'm looking for information on the similarities and differences between operations on numeric fractions and operations involving rational expressions.

Similarities: the processes all work in exactly the same way, whether you're working with numbers or with variables.
Differences: you can't simplify as much with variables as with numbers.

Also can you explain how to find the reciprocal of an expression.

In the usual way: flip it over.

Eliz.

 

[Mrspi]

Hi,

I'm looking for information on the similarities and differences between operations on numeric fractions and operations involving rational expressions. Also can you explain how to find the reciprocal of an expression.

Thanks so much,

Ladyhawk0965

Hi!

In answer to your first question, the only real difference I can see between operations with numeric fractions and operations with rational expressions is that when you are dealing with rational expressions, there usually are restrictions placed on the variables. If the denominator of a rational expression contains a variable, then that rational expression is only defined for values of the variable for which the denominator is not equal to 0. Similarly, if a variable appears in the numerator of a rational expression, then one must make sure that an operation like division (which involves the reciprocal of the divisor) is restricted so that the reciprocal exists....the variable cannot take on a value for which the numerator of the original expression is equal to 0.

How do you find the reciprocal? The same way you do for a numerical fraction. The reciprocal of a/b is 1/(a/b), or b/a. If numerator or denominator contains a variable, you need to note restrictions on the variable as discussed above.