Conduction with thermal energy generation

[yecko]

Homework Statement

I am wrong in my attempt, yet I can't figure out the reason why...
View attachment 230978

Homework Equations

View attachment 230979
(solution with h=250 W/m^2*K instead of 350 W/m^2*K)

The Attempt at a Solution

View attachment 231065
This is how I obtain the answers, which I checked all the calculations and I don't think there is numerical problem. I followed the steps in the solution manual, yet I am wrong and I don't know why.

Can anyone see anything going wrong here?
thank you so much!

 

[anorlunda]

The rules say that images should not be used in place of text. They can be hard to read for people using phones to access PF, but your images are pretty clear, so we'll allow them.

When you compose a new post, a button "LateX" at the lower left allows you to enter math directly.