1b)
∫ xsec²x dx
xtanx - ∫tanx dx
xtanx + ln(cosx)
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1d)
∫[1 0] tan(-1)x dx
let u = tan(-1)x
x = tanu
dx = sec²u du
at x = 1, u = π/4
at x = 0, u = 0
∫[π/4 0] u.sec²u du
using the result from 1b) this becomes,
[utanu + ln(cosu)][π/4 0]
{(π/4*1 + ln(1/√2)) - (0 + ln(1))}
π/4 - ½ln(2)
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1e)
∫[1 0] 1/(e^x + 1) dx
∫[1 0] (e^x + 1)/(e^x + 1) - (e^x)/(e^x + 1) dx
∫[1 0] 1 - (e^x)/(e^x + 1) dx
[x - ln(e^x + 1)] [1 0]
{(1 - ln(e + 1)) - (0 - ln(1+1))}
1 + ln(2/(e+1))
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2b)
∫[2 1] dx/root(x^2 - 1)
let x = cosht
dx = sinht dt
root(x^2 - 1)=√(cosh²t - 1) = √(sinh²t) = sinht.
at x = 2, t = cosh(-1)(2)
at x = 1, t = cosh(-1)(1)
∫sinht/sinht dt = ∫ 1 dt = [t][cosh(-1)(2) cosh(-1)(1)]
cosh(-1)(2) - cosh(-1)(1)
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d)
∫[∞ 2] dx/(x^2 - 1)^(3/2)
let x = cosht
dx = sinht dt
root(x^2 - 1)=√(cosh²t - 1) = √(sinh²t) = sinht.
at x = ∞, t = cosh(-1)(∞
= ∞
at x = 2, t = cosh(-1)(2)
∫sinht/sinh³t dt = ∫ 1/sinh²t dt = [cotht] [∞ 2]
1 - coth(2)
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