# Tutor profile: Shervin A.

## Questions

### Subject: Pre-Calculus

Simplify g = ln(e^5)

g =5

### Subject: Mechanical Engineering

How many types of heat transfer do you have pipe carrying hot water subjected to outdoor conditions in the winter and in the wind?

You have forced, external convection due to the pipe in cross flow, internal convection, and some conduction through the pipe surface that may be negligible depending on the material and insulation of the pipe.

### Subject: Calculus

y = x^3-9x. Find the roots and find the max and min of the function

setting y=0 x(x^2-9)=0 x =0; x =3,-3; Finding the derivatives of the function and setting it equal to zero: 3x^2-9x=0 x(3x-9)=0 x=0; x =3; Solving for the second derivative: y=6x-9, and now by plugging the max/min values we can determine which one is max and which one is min. y(0) =-9 (min) y(3) = 9 (max)

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