Shortcut 1: Differentiation Check Unsure of your answer? Differentiate it. If you get back the original integrand, you're correct. This takes 30 seconds and catches sign/coefficient errors.
Shortcut 2: Recognizing d/dx in Numerator Before any technique, check if the numerator is the derivative of the denominator (gives ln) or of the expression under a root. This solves ~30% of JEE integration problems instantly.
Shortcut 3: Standard Form Recognition Memorize these on sight:
- -> arctan
- -> ln||
- 1/sqrt(a^{2-x}^2) -> arcsin
- 1/sqrt(x^{2+a}^2) -> ln|x+sqrt(x^{2+a}^2)|
Shortcut 4: Splitting Linear Numerator Over Quadratic For integral dx: always split as px+q = lambda*(derivative of denominator) + mu This converts to ln + arctan immediately.
Shortcut 5: Trig Power Quick Results
- integral (x) dx = x/2 - sin + C
- integral (x) dx = x/2 + sin + C
- integral (x) dx = -cos(x) + cos^3$$\frac{x}{3} + C
- integral (x) dx = sin(x) - sin^3$$\frac{x}{3} + C
Shortcut 6: Use Options in MCQ If stuck, differentiate each option. The one whose derivative matches the integrand is correct. This is a valid strategy for difficult integrals in MCQ format.
Shortcut 7: integral f'(f(x)) dx = 2*sqrt(f(x)) + C Direct substitution result — saves time on many problems.
Shortcut 8: For integral +b*cos(x)) Write asin(x)+bcos(x) = sqrt(a^{2+b}^2)*sin(x+alpha). integral = integral csc(a^{2+b}^2) dx = standard csc integral.