# Tutor profile: Saurin H.

## Questions

### Subject: Chemistry

What is the electron pair geometry and molecular geometry of PBr5 (VSEPR)

First, draw Lewis Dot Structure. I can't really show that here, but PBr5 is a pretty simple structure to draw. First you find that it has 40 valence electrons, then you just start filling them out and it works without any complications. Note: P breaks the octet rule. Once you draw PBr5 you see that there are no lone pairs and the steric number is 5. This means that the electron pair geometry and molecular geometry are the same: they are both trigonal bipyramidal.

### Subject: Calculus

What is the derivative of f(g(x)) where g(x)=sinx and f(x)=5x^2 - 3x?

The derivative of f(g(x)) = f'(g(x))*g'(x) f(g(x)) = 5(sinx)^2 - 3sinx --> f'(g(x)) = 10sinxcosx - 3cosx g'(x) = cosx f'(g(x))*g'(x) = 10sinx(cosx)^2 - 3(cosx)^2 = (10sinx-3)*(cosx)^2

### Subject: Algebra

Solve for x, y, and z: (1.) x^2 + 3y - (5/4)z = 8 (2.) 2x^2 - 8y + (3/8)z = 3 (3.) (2/16)z + 7y = 2

2*(1.) = 2*(x^2 + 3y - (5/4)z = 8) --> 2x^2 + 6y - (10/4)z = 16 2*(1.) - (2.) --> 0x + 14y - (23/8)z = 13 2*(3.) --> 14y + (2/8)z = 4 [2*(1.) - (2.)] - 2*(3): 0y - (25/8)z = 9 --> (25/8)z=9 --> 25z=72 --> z=2.88 14y + (2/8)(2.88) = 4 --> y=.234 x^2 + 3(.234) - (5/4)(2.88) = 8 --> x=3.301 or -3.301 x=3.301 or -3.301, y=.234, z=2.88

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