Answer:
4
Step-by-step explanation:
The mean of a set of data: <em>(n₁ + n₂ + n₃...)/n</em>, where n₁,₂,₃... are numbers in the set, and n is the number of numbers.
Plug in: (1 + 5 + 5 + 7 + 3 + 3 + 4)/7
Add: 28/7
Divide: 4
Not of Bernoulli type, but still linear.

There's no need to find an integrating factor, since the left hand side already represents a derivative:
![\dfrac{\mathrm d}{\mathrm dx}[(1+x^2)y]=(1+x^2)\dfrac{\mathrm dy}{\mathrm dx}+2xy](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cmathrm%20d%7D%7B%5Cmathrm%20dx%7D%5B%281%2Bx%5E2%29y%5D%3D%281%2Bx%5E2%29%5Cdfrac%7B%5Cmathrm%20dy%7D%7B%5Cmathrm%20dx%7D%2B2xy)
So, you have
![\dfrac{\mathrm d}{\mathrm dx}[(1+x^2)y]=4x^2](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cmathrm%20d%7D%7B%5Cmathrm%20dx%7D%5B%281%2Bx%5E2%29y%5D%3D4x%5E2)
and integrating both sides with respect to

yields


Add it up then you will get answer