solvefor y,((d^3y))/((dx^3))+y=3+5e^x

解答

求解

y, \frac{( d ^{3} \cdot y )}{( d \cdot x ^{3} )} + y = 3 + 5 e^{x}

y = \frac{3 x ^{3} + 5 e ^{x} x ^{3}}{d ^{2} + x ^{3}}; x \neq = 0, d \neq = x - x, d \neq = - x - x

求解步骤

\frac{( d ^{3} y )}{( d x ^{3} )} + y = 3 + 5 e^{x}

消掉

\frac{d ^{3} y}{d x ^{3}} : \frac{d ^{2} y}{x ^{3}}

\frac{d ^{2} y}{x ^{3}} + y = 3 + 5 e^{x}

在两边乘以

x^{3}

d^{2} y + y x^{3} = 3 x^{3} + 5 e^{x} x^{3}; x \neq = 0

分解

d^{2} y + y x^{3} : y (d^{2} + x^{3})

y (d^{2} + x^{3}) = 3 x^{3} + 5 e^{x} x^{3}; x \neq = 0

两边除以

d^{2} + x^{3}; x \neq = 0, d \neq = x - x, d \neq = - x - x

y = \frac{3 x ^{3} + 5 e ^{x} x ^{3}}{d ^{2} + x ^{3}}; x \neq = 0, d \neq = x - x, d \neq = - x - x

x - \frac{9}{20} x = 1200

so l v e f or x, 8 x = 7 - 5 y

\frac{x}{2} + \frac{x}{4} + \frac{x}{5} + 1000 = x

so l v e f or m, - 3 m + n = - 13 m + 2

so l v e f or a, a^{2} + b^{2} = (a - b)^{2}