Hello, I just wanted to verify this definite integral and if my answer is good:
a = 1 and b = 4
integral of
(1 - 1/x^2)(x^2 + 1/x) dx
= (x + 1/x)(x^3/3 + lnx) + C
(4 + 1/4)(64/3 + ln4) - (1 + 1)(1/3 + ln1)
= 96.56 - 0.6666 = 95.89
Thank you
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Answers & Comments
Verified answer
4
= ∫ (1 – 1 ⁄ x²) • (x² + 1 ⁄ x) dx ... expand
1
4
= ∫ [ x² + (1 ⁄ x) – 1 – (1 ⁄ x³) ] dx ... integrate each term
1
= (x³ ⁄ 3) + ln[x] – x + (1 ⁄ (2x²)) ... evaluated [1, 4]
= (4³ ⁄ 3) + ln[4] – 4 + (1 ⁄ 32) – [ (1³ ⁄ 3) + ln[1] – 1 + (1 ⁄ (2x²)) ]
= 18.75 + 0.1667
= 18.92
No it's not good, you can only integrate term by term when you are adding (or subtracting the terms) not multiplying.
You have to multiply the binomials before integrating.
The integrand is:
x^2 + 1/x - 1 - 1/x^3 dx
x^2 + 1/x -1 - x^-3 dx
=> x^3/3 + ln|x| - x + 1 / (2x^2) | from 1 to 4