Real Analysis Practice (Interactive)

Intuition

Rigorous calculus: Real analysis puts calculus on a rigorous foundation, it defines limits, continuity, and derivatives with epsilon-delta precision, removing the hand-waving of introductory calculus. It is where you learn to think like a mathematician.

Why it matters: Real analysis is the bedrock of all analysis, it teaches you to construct rigorous proofs, understand convergence, and reason about infinite processes. These skills transfer to every area of mathematics.

The key insight: Limits are about “arbitrarily close”, for any precision you demand, the function eventually gets that close. This simple idea, made rigorous, resolves centuries of confusion about infinitesimals and infinite series.

University Mathematics, Real Analysis Practice

10 auto-graded practice problems at medium to hard difficulty. Select an answer, submit, and review the explanation.

Sequences and Convergence

Limits, Continuity, and Differentiation

Integration

Common Mistakes

Confusing pointwise and uniform convergence: A sequence of continuous functions can converge pointwise to a discontinuous function (e.g., $f_n(x) = x^n$ on $[0,1]$). Uniform convergence preserves continuity, but pointwise convergence does not. Always check whether the convergence is uniform before concluding the limit function inherits properties like continuity or integrability.

Assuming continuity implies differentiability: The function $f(x) = |x|$ is continuous everywhere but not differentiable at $x = 0$. Continuity is necessary but not sufficient for differentiability. The intermediate value theorem applies to continuous functions, but the mean value theorem requires differentiability on the open interval.

Confusing conditional and absolute convergence: A series like $\sum (-1)^n / n$ converges conditionally but not absolutely. Rearranging the terms of a conditionally convergent series can change its sum (Riemann’s rearrangement theorem). Always test $\sum |a_n|$ separately when determining convergence properties.

Cross-References

• Site Home: Main landing page for Mathematics notes.
• Linear Algebra: Vector spaces, matrices, and linear transformations.
• Real Analysis: Rigorous treatment of real numbers and calculus.
• Practice: Practice problems for revision.