1.

`int((x^4-1)dx)/(x^2sqrt(x^4+x^2+1))`A. `sqrt((x^(4) + x^(2) + 1)/(x)) + c`B. `sqrt(x^(4) + 2 - (1)/(x^(2))) + c`C. `sqrt(x^(2) + (1)/(x^(2)) + 1) + c`D. `sqrt((x^(4) - x^(2) + 1)/(x)) + c`

Answer» Correct Answer - C
Take option (a)
`I_(1) = sqrt((x^(4) + x^(3) + 1)/(x)) + C`
`(dI_(1))/(dx) = (d)/(dx) [(x^(3) + x^(2) + x^(-1))^(1//2) + C]`
`(dI_(2))/(dx) = (1)/(2) (x^(3) + x^(2) + x^(-1))^(-1//2) (3x^(2) + 2x - x^(-2))`
`= (1)/(2) [(3x^(2) + 2x - (1)/(x^(2)))/(sqrt(x^(3) + x^(2) + (1)/(x)))]`
`(dI_(2))/(dx) = (1)/(2) [(3x^(4) + 2x^(3) - 1)/((x^(2))/(sqrtx) sqrt(x^(4) + x^(3) + 1))]`
Take option (b) :
`I_(2) = sqrt(x^(4) + 2 - (1)/(x^(2))) + C`
`(dI_(2))/(dx) = (1)/(2) [x^(4) + 2 - x^(-2)]^(-1//2) [4x^(3) + 0 + 2x^(-3)]`
`= (1)/(2) [(4x^(3) + (2)/(x^(3)))/(sqrt(x^(4) + 2 - (1)/(x^(2))))] = (2x^(6) + 1)/((x^(3))/(x) sqrt(x^(6) + 2x^(2) - 1))`
`(dI_(2))/(dx) = (2x^(6) + 1)/(x^(2) sqrt(x^(6) + 2x - 1))`
Take option (c)
`I_(3) = sqrt(x^(2) + x^(-2) + 1) + C`
`(dI_(3))/(dx) = (1)/(2) [x^(2) + x^(-2) + 1]^(-1//2) [2x - 2x^(-3) + 0]`
`= (1)/(2) [(2x - (2)/(x^(3)))/(sqrt(x^(2) + (1)/(x^(2)) + 1))] = (1)/(2) [(2(x^(4) -1))/(x^(3) sqrt((x^(4) + 1 + x^(2))/(x^(2))))]`
`(dI_(3))/(dx) = (x^(4) -1)/(x^(2) sqrt(x^(4) + x^(2) + 1))`


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