BeginnerTopic 25 of 104Engineering Mathematics
Limits
The value a function approaches as input approaches a point; the foundation of calculus.
In depth
The limit of f(x) as x→a is the value f approaches. Limits define derivatives and integrals. Techniques: substitution, factoring, rationalising, squeeze theorem and L'Hôpital's rule for 0/0 or ∞/∞ forms.
Key points
- One-sided limits can differ
- Limits at infinity describe asymptotes
- lim sin x/x =1 as x→0
Examplelim (x²-1)/(x-1) as x→1 equals 2 after cancelling (x-1).
Limits describe what happens near a point, and they define derivatives and integrals, so every calculus method depends on them.
What is Limits?
The value a function approaches as input approaches a point; the foundation of calculus.
Why is it important to understand limits?
Limits describe what happens near a point, and they define derivatives and integrals, so every calculus method depends on them.
What is L'Hopital's rule for?
It evaluates limits of the form zero over zero or infinity over infinity by taking derivatives of the top and bottom.
Does a limit exist if the function is undefined at the point?
Yes. A limit depends on values near the point, not on the value at the point itself.
How is Limits used in practice?
Typical applications include finding the value of a ratio when both numerator and denominator go to zero, describing the steady-state value of a response as time goes to infinity and checking a safety limit as load approaches a maximum.
What should I learn before Limits?
Study "Euler's formula" first (topic 24 of 104 in Engineering Mathematics). It covers the groundwork this topic builds on.
What are the key points of Limits?
One-sided limits can differ. Limits at infinity describe asymptotes. lim sin x/x =1 as x→0.
Can you give an example of Limits?
lim (x²-1)/(x-1) as x→1 equals 2 after cancelling (x-1).
What comes after Limits?
The next topic is "Continuity", which builds directly on this one.
How difficult is Limits?
It is classed as Beginner in Engineering Mathematics (topic 25 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.