Question

can someone please check my derivatives...

Answer 1

\[y=(Ax ^{2}+Bx)sinx +(Dx ^{2}+Ex)cosx\]

Answer 2

\[y \prime=(2Ax+B)sinx+(Ax ^{2}+Bx)cosx+(2Dx+E)cosx-(Dx ^{2}+Ex)sinx\]

Answer 3

The first one looks good. Do they want you to combine the terms?

Answer 4

\[y \prime \prime=2Asinx+(4Ax+2B)cosx-(Ax ^{2}+Bx)sinx+2dcosx-(4Dx+2E)sinx+(Dx ^{2}+Ex)cosx\]

Answer 5

yes, would be easy for me because I have plug these back into a differential equation.

Answer 6

Ok :)

Answer 7

can u guys see the 2nd one?

Answer 8

Yes

Answer 9

lower case d = upper case D....sorry.

Answer 10

Thanks

Answer 11

the differential equation is:\[y \prime \prime+y=2xsinx\]

Answer 12

I am messing up in the algebra part somewhere because am getting the wrong coefficients.

Answer 13

I got a little lost on the second derivative. I see where you got the 2Asinx, but am not seeing how you got the (4A + 2B)cosx

Answer 14

since for the second expression I got (2Ax + b)cosx

Answer 15

well i combined two:\[(2Ax+B)cosx\]

Answer 16

Ok, thanks :) I will keep going, then!

Answer 17

yeah there will be another combination with the two sine terms.

Answer 18

@dan815