1 | ||
− | ∫xex*e−14x2 | |
4 |
1 | ||
− | ∫ex(xe−14x2)dx | |
4 |
d | −1 | ||
e−14x2 = ( | )*2x*e−14x2 | ||
dx | 4 |
d | 1 | ||
e−14x2 = − | xe−14x2 | ||
dx | 2 |
1 | 1 | 1 | ||||
− | ∫ex(xe−14x2)dx = ∫( | ex)(− | xe−14x2)dx | |||
4 | 2 | 2 |
1 | 1 | |||
= | ex−14x2− | ∫ex−−14x2dx | ||
2 | 2 |
1 | 1 | |||
= | ex−14x2− | ∫e−(14x2−x+1−1) | ||
2 | 2 |
1 | 1 | |||
= | ex−14x2− | ∫e1−(12x−1)2dx | ||
2 | 2 |
1 | e | |||
= | ex−14x2− | ∫e−(12x−1)2dx | ||
2 | 2 |
1 | |
x−1 = t | |
2 |
1 | |
dx = dt | |
2 |
1 | ||
= | ex−14x2−e∫e−t2dt | |
2 |
1 | e√π | 1 | ||||
= | ex−14x2− | erf( | x−1)+C | |||
2 | 2 | 2 |
1 | e√π | 1 | ||||
= | ex−14x2+ | erf(1− | x)+C | |||
2 | 2 | 2 |