(VERY BASIC)INTEGRATION DOUBTS........

1.I=\int cosh^2(8x+5)dx

2.I=\int \frac{dx}{(x^2+x+1)}

3.I=\int\frac{(2+3x^2)dx}{[x^2(1+x^2)]}..

4.I=\int\frac{(x^2-1)dx}{(x^4+3x^2+1)arctan[(x^2+1)/x]}

5.I=\int \frac{(\sqrt{a^2-x^2})dx}{x^4}

plzz help me m a begginer nd post ur full solutions rather than half nd hintsplzzzzzzzzzzz[1][132][1]

15 Answers

1
rahul nair ·

2.I=\int 1/[(x+1/2)^{2}+(\sqrt{3}/4)^{2}]dx

which is of the form dx/x2+a2

1
sanchit ·

arre bhaii ye kaise kiya???????????????any method.........................or as usual it needs practice

29
govind ·

@Sanchit..this method is called making a pefect square..u may be familiar with it..

1
sanchit ·

actually m not

1
rahul nair ·

these r very basics ques.........
I think u need to read the theory and formulae before proceeding......[1]

39
Pritish Chakraborty ·

To make perfect square, take coefficient of middle term, or x, half it and then square it and add/subtract to expression
x2 + x + 1 = x2 + x + 1/4 - 1/4 + 1 = (x + 1/2)2 -1/4 + 1 = (x + 1/2)2 + 3/4 = (x + 1/2)2 + (√3/2)2

1
sanchit ·

hey is IA maron right for beggining cozz its the first time m learning itegrals nd m studying from it

1
sanchit ·

@ pritish bhaiiya thnxx i have to work o0n it

39
Pritish Chakraborty ·

you'll get a better hang of it from NCERT 12th class book :)

29
govind ·

@sanchit...Try NCERT first ..it contains around 500 problems on integration...then only proceed to any other book...

1
sanchit ·

hmmm right m gonna do it first

1
" ____________ ·

we know

many other methods der

1
" ____________ ·

now there fore

put 16 x + 10 = u 16 dx = du dx = du /16

now u can do it further !!!!!

other method

cosh2 x = 1 + cos h(2x ) 2

is this formula valid

1
" ____________ ·

for second one

ax ^ 2 + bx + c

for completing a perfect square

first the coefficient of x 2 must be 1 .

then

ADD AND SUBTRACT ( 12 . COEFFICIENT OF X ) 2

EX .

2. x^2 + x + 1 = x ^2 + x + 1 + ( 1/2 ) ^2 - ( 1 /2 ) ^2

combine the ones in bold and others

x2+ x + 14 + 1 - 14

( x + 12 )2 + 34

1
" ____________ ·

for integration after ncert

this book is best

http://www.askiitians.com/book-review/IIT-JEE-Mathematics-Arihant-Integral-Calculus

ur doubts are good they are not of basic level as u think

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