Part of CALC-04 — Indefinite Integration

Integration Involving Exponential and Logarithmic Functions

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Exponential Integrals:

integral e^(ax)sin(bx) dx = e^(ax)(asin(bx) - bcos(bx))/(a^{2+b}^2) + C integral e^(ax)cos(bx) dx = e^(ax)(acos(bx) + bsin(bx))/(a^{2+b}^2) + C (Derived by applying by parts twice and solving for I)

integral xnx^n * exe^x dx: use by parts n times (tabular method) integral exe^x * xnx^n = exe^x * (sumk=0nsum_{k=0}^{n} (-1)^k * n!/(n-k)! * x^(n-k)) + C

Logarithmic Integrals:

integral ln(x) dx = xln(x) - x + C integral (ln(x))^2 dx = x(ln(x))^2 - 2xln(x) + 2x + C integral xnx^n * ln(x) dx = x^(n+1)[lnx(n+1)\frac{x}{(n+1)} - 1n+1\frac{1}{n+1}^2] + C (for n != -1) integral lnxx\frac{x}{x} dx = (ln(x))^2/2 + C (substitution u = ln(x))

Special Exponential Forms:

integral e^(sqrt(x)) dx: Let t = sqrt(x), x = t2t^2, dx = 2t dt = 2integral tete^t dt = 2ete^t(t-1) + C = 2e^(sqrt(x))(sqrt(x)-1) + C

integral exe^x * x1x\frac{x-1}{x}^2 dx: Write x1x\frac{x-1}{x}^2 = 1/x - 1/x2x^2. Note d/dx1x\frac{1}{x} = -1/x2x^2. So this is exe^x[f(x) + f'(x)] with f = 1/x... wait: f(x) + f'(x) = 1/x + (-1/x2x^2) = 1/x - 1/x2x^2 = x1x\frac{x-1}{x}^2. Yes! integral = exe^x/x + C

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