- #1
asdf1
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for the following question:
y``+y`+9.25y=2+2x+x^2
my problem:
yh=c1+c2e^(-x)
suppose yp=c3x^2 + c4x+c5
then yp`=2c3x+c4
so yp``=2c3
then 2c3+2c3x+c4=2+2X+X^2
so c3=1, c4=1
so yp=x^2+x
then y=c1+c2e^(-x)+x^2+x
which implies c1=8
=> y=8+c2e^(-x)+x^2+x
so y`=-c2e^(-x)+2x+1
so -1=-c2+1 =>c2=2
then y=8+2e^(-x)+x^2 +x
but the correct answer should be 3e^(-x)+5+2x+(1/3)x^3
does anybody know what's wrong with the calculations?
y``+y`+9.25y=2+2x+x^2
my problem:
yh=c1+c2e^(-x)
suppose yp=c3x^2 + c4x+c5
then yp`=2c3x+c4
so yp``=2c3
then 2c3+2c3x+c4=2+2X+X^2
so c3=1, c4=1
so yp=x^2+x
then y=c1+c2e^(-x)+x^2+x
which implies c1=8
=> y=8+c2e^(-x)+x^2+x
so y`=-c2e^(-x)+2x+1
so -1=-c2+1 =>c2=2
then y=8+2e^(-x)+x^2 +x
but the correct answer should be 3e^(-x)+5+2x+(1/3)x^3
does anybody know what's wrong with the calculations?