# Tutor profile: Ben C.

## Questions

### Subject: Spanish

Fill in the blanks: Mi hermana siempre se ___ enojada cuando ella __ que caminar con el perro.

Mi hermana siempre se __pone__ enojada cuando ella _tiene_ que caminar con el perro. (My sister always gets mad when she has to walk the dog).

### Subject: Chemistry

Calculate the molar mass of $$H_2O$$

Hydrogen has a molar mass of 1, and Oxygen has a molar mass of 16. Therefore, the molar mass is $$1*16 + 2*1 = 18$$.

### Subject: Calculus

Evaluate the following derivative at $$x=2$$ $$ \frac{\partial }{\partial x} (5x^3 + 4x^2 - 2x - 7)$$

First we take the derivative of the expression using the power rule: $$ \frac{\partial }{\partial x} (5x^3 + 4x^2 - 2x - 7) = 3*5x^{3-1} + 2*4x^{2-1} - 2*1x^{1-1} - 0 = 15x^2 + 8x - 2$$ Then we evaluate it for $$x=2$$: $$15(2^2) + 8(2) - 2 = 15(4) + 16 - 2 = 60 + 16 - 2 = 74$$

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