Limit with the quotient law

In this case, the common denominator would be ##3x##. After finding the common denominator, the problem becomes ## \frac {3-3x} {3x (x-3)} ##. From here, you may notice that the numerator can be factored as ##-3(3x - 1)##. This then simplifies to ## \frac {-3} {3x} ##. Cancel out the 3's, and you will end up with ## \frac {-1} x ##. Now, substitute 3 back into x to get the answer of ##-\frac 1 3##.In summary, to solve the given limit
  • #1
Alice7979
36
2

Homework Statement


lim (1/x - 1/3) / (x-3)
x->3

Homework Equations

The Attempt at a Solution


I tried to cancel the bottom (x-3) out by multiplying the top by 3/3 and x/x and then got ((3-x)/3x)/(x-3) but ended with 0/0 and the right answer is -1/9. The top part is confusing me.
 
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  • #3
Alice7979 said:

Homework Statement


lim (1/x - 1/3) / (x-3)
x->3

Homework Equations

The Attempt at a Solution


I tried to cancel the bottom (x-3) out by multiplying the top by 3/3 and x/x and then got ((3-x)/3x)/(x-3) but ended with 0/0 and the right answer is -1/9. The top part is confusing me.
Combine the two fractions in the numerator, and then simplify. This problem isn't much more than an exercise in working with fractions.
 
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Likes Delta2 and scottdave
  • #4
Like @Mark44 said, find a common denominator between ## \frac 1 x \text{ and } \frac 1 3 ##. Similar to if you were adding the fractions ## \frac 1 7 \text{ and } \frac 1 3 ##
 

What is the quotient law for limits?

The quotient law for limits states that the limit of a quotient is equal to the quotient of the limits of the individual functions, as long as the limit of the denominator is not equal to zero.

How do you apply the quotient law to find limits?

To apply the quotient law, you first find the limits of the numerator and denominator separately. Then, you can take the quotient of these limits to find the overall limit.

What happens if the limit of the denominator is zero?

If the limit of the denominator is zero, the quotient law cannot be applied. This is because dividing by zero is undefined in mathematics.

Can the quotient law be used for all types of functions?

Yes, the quotient law can be used for all types of functions, as long as the limit of the denominator is not equal to zero.

Are there any other laws for finding limits?

Yes, there are other laws for finding limits, such as the sum and difference laws, product law, and power law. These laws can be used in combination with the quotient law to find limits of more complex functions.

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