来自金世伟的问题
已知fn(x)满足fn′(x)=fn(x)+xn-1ex(n为正整数)且fn(1)=en,求函数项级数∞n=1fn(x)之和.
已知fn(x)满足fn′(x)=fn(x)+xn-1ex(n为正整数)且fn(1)=en,求函数项级数∞n=1fn(x)之和.
1回答
2020-12-28 06:29
已知fn(x)满足fn′(x)=fn(x)+xn-1ex(n为正整数)且fn(1)=en,求函数项级数∞n=1fn(x)之和.
已知fn(x)满足fn′(x)=fn(x)+xn-1ex(n为正整数)且fn(1)=en,求函数项级数∞n=1fn(x)之和.
由已知条件可得,fn′(x)-fn(x)=xn-1ex,
由一阶线性非齐次微分方程的通解公式可得:
fn(x)=ex(∫xn-1dx+C)=e