解
∫4x2+1x4dx
解
8(2563lntan(21arctan(x))+1−256(tan(21arctan(x))+1)3+256(tan(21arctan(x))+1)21+64(tan(21arctan(x))+1)31−128(tan(21arctan(x))+1)41−2563lntan(21arctan(x))−1−256(tan(21arctan(x))−1)3−256(tan(21arctan(x))−1)21+64(tan(21arctan(x))−1)31+128(tan(21arctan(x))−1)41)+C
解答ステップ
∫4x2+1x4dx
定数を除く: ∫a⋅f(x)dx=a⋅∫f(x)dx=41⋅∫x2+1x4dx
三角関数による置換を適用する
=41⋅∫tan4(u)sec(u)du
三角関数の公式を使用して書き換える
=41⋅∫cos5(u)sin4(u)du
u置換積分法を適用する
=41⋅∫(1−v2)532v4dv
定数を除く: ∫a⋅f(x)dx=a⋅∫f(x)dx=41⋅32⋅∫(1−v2)5v4dv
以下の部分分数を得る: (1−v2)5v4:256(v+1)3+256(v+1)23−128(v+1)31−64(v+1)43+32(v+1)51−256(v−1)3+256(v−1)23+128(v−1)31−64(v−1)43−32(v−1)51
=41⋅32⋅∫256(v+1)3+256(v+1)23−128(v+1)31−64(v+1)43+32(v+1)51−256(v−1)3+256(v−1)23+128(v−1)31−64(v−1)43−32(v−1)51dv
総和規則を適用する: ∫f(x)±g(x)dx=∫f(x)dx±∫g(x)dx=41⋅32(∫256(v+1)3dv+∫256(v+1)23dv−∫128(v+1)31dv−∫64(v+1)43dv+∫32(v+1)51dv−∫256(v−1)3dv+∫256(v−1)23dv+∫128(v−1)31dv−∫64(v−1)43dv−∫32(v−1)51dv)
∫256(v+1)3dv=2563ln∣v+1∣
∫256(v+1)23dv=−256(v+1)3
∫128(v+1)31dv=−256(v+1)21
∫64(v+1)43dv=−64(v+1)31
∫32(v+1)51dv=−128(v+1)41
∫256(v−1)3dv=2563ln∣v−1∣
∫256(v−1)23dv=−256(v−1)3
∫128(v−1)31dv=−256(v−1)21
∫64(v−1)43dv=−64(v−1)31
∫32(v−1)51dv=−128(v−1)41
=41⋅32(2563ln∣v+1∣−256(v+1)3−(−256(v+1)21)−(−64(v+1)31)−128(v+1)41−2563ln∣v−1∣−256(v−1)3−256(v−1)21−(−64(v−1)31)−(−128(v−1)41))
代用を戻す
=41⋅322563lntan(2arctan(x))+1−256(tan(2arctan(x))+1)3−−256(tan(2arctan(x))+1)21−−64(tan(2arctan(x))+1)31−128(tan(2arctan(x))+1)41−2563lntan(2arctan(x))−1−256(tan(2arctan(x))−1)3−256(tan(2arctan(x))−1)21−−64(tan(2arctan(x))−1)31−−128(tan(2arctan(x))−1)41
簡素化 41⋅322563lntan(2arctan(x))+1−256(tan(2arctan(x))+1)3−−256(tan(2arctan(x))+1)21−−64(tan(2arctan(x))+1)31−128(tan(2arctan(x))+1)41−2563lntan(2arctan(x))−1−256(tan(2arctan(x))−1)3−256(tan(2arctan(x))−1)21−−64(tan(2arctan(x))−1)31−−128(tan(2arctan(x))−1)41:8(2563lntan(21arctan(x))+1−256(tan(21arctan(x))+1)3+256(tan(21arctan(x))+1)21+64(tan(21arctan(x))+1)31−128(tan(21arctan(x))+1)41−2563lntan(21arctan(x))−1−256(tan(21arctan(x))−1)3−256(tan(21arctan(x))−1)21+64(tan(21arctan(x))−1)31+128(tan(21arctan(x))−1)41)
=8(2563lntan(21arctan(x))+1−256(tan(21arctan(x))+1)3+256(tan(21arctan(x))+1)21+64(tan(21arctan(x))+1)31−128(tan(21arctan(x))+1)41−2563lntan(21arctan(x))−1−256(tan(21arctan(x))−1)3−256(tan(21arctan(x))−1)21+64(tan(21arctan(x))−1)31+128(tan(21arctan(x))−1)41)
定数を解答に追加する=8(2563lntan(21arctan(x))+1−256(tan(21arctan(x))+1)3+256(tan(21arctan(x))+1)21+64(tan(21arctan(x))+1)31−128(tan(21arctan(x))+1)41−2563lntan(21arctan(x))−1−256(tan(21arctan(x))−1)3−256(tan(21arctan(x))−1)21+64(tan(21arctan(x))−1)31+128(tan(21arctan(x))−1)41)+C