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Revision: Integration Maths HSC Commerce (English Medium) 12th Standard Board Exam Maharashtra State Board

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Formulae [4]

Formula: Standard Integration Formulae
Integral Result
\[\int x^ndx\] \[\frac{x^{n+1}}{n+1}+C\]
\[\int(ax+b)^ndx\] \[\frac{(ax+b)^{n+1}}{a(n+1)}+C\]
\[\int\frac{1}{x}dx\] \[log/x/+c\]
\[\int\frac{1}{ax+b}dx\] \[\frac{\log\left|ax+b\right|}{a}+c\]
\[\int a^xdx\] \[\frac{a^x}{\log a}+C\]
\[\int a^{px+q}dx\] \[\frac{a^{px+q}}{p\log a}+C\]
\[\int e^xdx\] \[e^{x}+C\]
\[\int e^{px+q}dx\] \[\frac{e^{px+q}}{p}+C\]
Formula: Standard Integrals of Quadratic Forms
  • \[\int\frac{1}{x^2-a^2}dx=\frac{1}{2a}log\left|\frac{x-a}{x+a}\right|+c\]

  • \[\int\frac{1}{a^2-x^2}dx=\frac{1}{2a}log\left|\frac{a+x}{a-x}\right|+c\]

  • \[\int\frac{1}{\sqrt{x^2+a^2}}dx=log\left|x+\sqrt{x^2+a^2}\right|+c\]

  • \[\int\frac{1}{\sqrt{x^2-a^2}}dx=log\left|x+\sqrt{x^2-a^2}\right|+c\]

Formula: Change of Variable
  • \[\int
    \begin{bmatrix}
    f(x)
    \end{bmatrix}^nf^{\prime}(x)dx=\frac{
    \begin{bmatrix}
    f(x)
    \end{bmatrix}^{n+1}}{(n+1)}+c\]
  • \[\int\left[\frac{f^{\prime}(x)}{f(x)}\right]dx=\log f(x)+c\]

  • \[\int\left[\frac{f^{\prime}(x)}{\sqrt{f(x)}}\right]dx=2\sqrt{f(x)}+c\]

  • \[\int\left[\frac{f^{\prime}(x)}{\sqrt[n]{f(x)}}\right]dx=\frac{n\sqrt[n]{\left[f(x)\right]^{n-1}}}{n-1}+c\]

Formula: Partial Fractions
Type Rational Form Partial Fraction Form
1 \[\frac{px\pm q}{(x-a)(x-b)}\] \[\frac{A}{x-a}+\frac{B}{x-b}\]
2 \[\frac{px^2\pm qx\pm r}{(x-a)(x-b)(x-c)}\] \[\frac{A}{x-a}+\frac{B}{x-b}+\frac{C}{x-c}\]
3 \[\frac{px\pm q}{\left(x-a\right)^2}\] \[\frac{A}{x-a}+\frac{B}{\left(x-a\right)^2}\]
4 \[\frac{px^2\pm qx\pm r}{(x-a)^2(x-b)}\] \[\frac{A}{x-a}+\frac{B}{\left(x-a\right)^2}+\frac{C}{x-b}\]
5 \[\frac{px^2\pm qx\pm r}{(x-a)^3(x-b)}\] \[\frac{A}{x-a}+\frac{B}{\left(x-a\right)^2}+\frac{C}{\left(x-a\right)^3}+\frac{D}{x-b}\]
6 \[\frac{px^2\pm qx\pm r}{(x-a)(ax^2\pmb x\pm c)}\] \[\frac{A}{x-a}+\frac{Bx+C}{ax^2 \pm b\pmb x\pm c}\]

Theorems and Laws [3]

Prove that: `int sqrt(a^2 - x^2) * dx = x/2 * sqrt(a^2 - x^2) + a^2/2 * sin^-1(x/a) + c`

Let I = `int sqrt(a^2 - x^2) dx`

= `int sqrt(a^2 - x^2)*1 dx`

= `sqrt(a^2 - x^2)* int 1 dx - int [d/dx (sqrt(a^2 - x^2))* int 1 dx]dx`

= `sqrt(a^2 - x^2)*x - int [1/(2sqrt(a^2 - x^2))*d/dx (a^2 - x^2)*x]dx`

= `sqrt(a^2 - x^2)*x - int 1/(2sqrt(a^2 - x^2))(0 - 2x)*x  dx`

= `sqrt(a^2 - x^2)*x - int (-x)/sqrt(a^2 - x^2)*x  dx`

= `xsqrt(a^2 - x^2) - int (a^2 - x^2 - a^2)/sqrt(a^2 - x^2)dx`

= `xsqrt(a^2 - x^2) - int sqrt(a^2 - x^2)dx + a^2 int dx/sqrt(a^2 - x^2)`

= `xsqrt(a^2 - x^2) - I + a^2sin^-1(x/a) + c_1`

∴ 2I = `xsqrt(a^2 - x^2) + a^2sin^-1(x/a) + c_1`

∴ I = `x/2 sqrt(a^2 - x^2) + a^2/2 sin^-1(x/a) + c_1/2`

∴ `int sqrt(a^2 - x^2)dx = x/2 sqrt(a^2 - x^2) + a^2/2sin^-1(x/a) + c`, where `c = c_1/2`.

Theorem: Change of Variable

If x = ϕ(t), then \[\int f(x)dx=\int f(\phi(t))\phi^{\prime}(t)dt\]

Theorem: Integration by Parts

If u and v are two functions of x, then

\[\int u.vdx=u\int vdx-\int\left[\int vdx.\frac{du}{dx}\right]dx\]

Key Points

Key points: Rules of Integration

Sum Rule:

\[\int[f(x)+g(x)]dx=\int f(x)dx+\int g(x)dx\]

Difference Rule:

\[\int[f(x)-g(x)]dx=\int f(x)dx-\int g(x)dx\]

Constant Multiple Rule:

\[\int kf(x)dx=k\int f(x)dx\]

Substitution Result:

If  \[\int f(x)dx=F(x)+C\] Then \[\int f(ax+b)dx=\frac{1}{a}F(ax+b)+C\]

Key Points: LAE Rule

L → A → E

  • L = Logarithmic (log x)

  • A = Algebraic (x, x², polynomial)

  • E = Exponential (eˣ)

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