Find the value of the integral:
∫ 2 x 2 − x + 1 6 x 4 − 5 x 3 + 4 x 2
If the value can be expressed as:
a 1 . x 3 − a 2 x 2 + a 3 1 . l n ( ∣ a 4 x 2 − x + 1 ∣ ) + a 5 a 6 1 . t a n − 1 ( a 8 a 7 x − 1 ) + C ...... where C is the constant of integration
Find the value of i = 1 ∑ 8 a i
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Good solution! It is on level 1 because at this stage you don't have much amount of followers. I am Resharing it so that it may get to some level!!
Ps:laborious one!
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yes... only requires hard work to solve this :/
still, i found it worth sharing because of the complications..
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You shall post problems on definite integration
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We have:
∫ 2 x 2 − x + 1 6 x 4 − 5 x 3 + 4 x 2 d x
= ∫ 2 x 2 − x + 1 x 2 ( 3 ( 2 x 2 − x + 1 ) − 2 x + 1 ) d x
= ∫ 3 x 2 d x − ∫ 2 x 2 − x + 1 x ( 2 x 2 − x + 1 − 1 ) d x
= ∫ 3 x 2 d x − ∫ x d x + 4 1 ∫ 2 x 2 − x + 1 4 x − 1 + 1 d x
= ∫ 3 x 2 d x − ∫ x d x + 4 1 [ ∫ 2 x 2 − x + 1 4 x − 1 d x + ∫ ( 2 x − 2 1 ) 2 + ( 2 7 ) 2 2 d x ]
Now:
∫ 2 x 2 − x + 1 4 x − 1 d x = ∫ 2 x 2 − x + 1 d ( 2 x 2 − x + 1 ) = l n ( ∣ 2 x 2 − x + 1 ∣ )
also,
∫ ( 2 x − 2 1 ) 2 + ( 2 7 ) 2 2 d x = ∫ ( 2 x − 2 1 ) 2 + ( 2 7 ) 2 d ( 2 x − 2 1 ) = 7 2 t a n − 1 7 4 x − 1
∴ we get 1 . x 3 − 2 x 2 + 4 1 l n ( ∣ 2 x 2 − x + 1 ∣ ) + 2 7 1 t a n − 1 7 4 x − 1
comparing, we get:
a 1 = 1 ; a 2 = 2 ; a 3 = 4 ; a 4 = 2 ; a 5 = 2 ; a 6 = 7 ; a 7 = 4 ; a 8 = 7
our sum: 2 9