Tolong dibantu kak.. Usm stis

∫dx/(e^x + 1)

misal, e^x + 1 = u
e^x = u - 1
e^x dx = du
dx = du/(e^x)
dx = du/(u - 1)

∫dx/(e^x + 1) = ∫(du/(u - 1))/u
= ∫du/(u(u - 1))
= ln|u - 1| - ln|u| + C
= ln |(u - 1)/u| + C
= ln|e^x/(e^x + 1)| + C
= ln|(e^x + 1)/(e^x)|^(-1) + C
= -ln|(e^x + 1)/(e^x)| + C
= -ln|1 + 1/e^x| + C
= -ln|1 + e^(-x)| + C

Jawaban tidak ada dalam opsi.