# Homework Help: Heat conduction through a layers of different materials

1. Nov 10, 2017

### curiosity colour

1. The problem statement, all variables and given/known data
Question C(ii)

2. Relevant equations
dQ/dt =-kA(dθ/dx)
dQ/dt = (θ12)/ ((lx/kxAx)+ (ly/kyAy))
3. The attempt at a solution
So the first time I tried at this question, I was using the second equation provided above,but when I check the answer, they put the area on the numerator. which left me wonder, how did they make it on top, I've check my textbook but none of it give any clues. If area is on the numerator with θ, I think k should be too isnt it?

2. Nov 10, 2017

### mjc123

If Ax = Ay = A, you can multiply numerator and denominator by A, so A will appear in the numerator and not the denominator. You can do the same with k if kx = ky, but that is not the case in this problem.

3. Nov 10, 2017

### Staff: Mentor

I’ve moved this to the precalculus math forum where they can help you learn algebra.

4. Nov 10, 2017