工程數學有些問題想指教大大

最近剛上工數課程很多都不會而老師卻出題目都看不懂
想請各位大大麻煩解一下

請利用參數變換法解下列DE
1. y" - 3y' + 2y = e^x
2. y" + y' = sec(x)
3. y" + 9y = csc(3x)/4
4. y" - 4y' + 4y = (x+1)e^2x

針對各給定 ay" + by' + cy = f(x)求通解
1. y" - 2y' - 8y = 8
2. y" + y' - 2y = 2x - 1
3. y" - y = sin(x)
4. y" + y = sin(x)
5. y" - y' - 20y = e^5x
6. y" + 5y' = -5
7. y"' + 6y" + 11y' + 6y = e^x
8. y"' + 25y' = e^-x
9. y" - 4y' - 12y = 3e^5x
10. y" - 4y' - 12y = 3e^6x
11. y" + 4y' - 2y = 2x^2 - 3x + 6

寫完是寫完了只是老師沒有給答案可是又想對對看是否正確
再麻煩各位大大幫忙協助