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# Calculus/Expert Profile

## Paul Klarreich

On Vacation
returns 12/05/2017
##### Expertise

All topics in first-year calculus including infinite series, max-min and related rate problems. Also trigonometry and complex numbers, theory of equations, exponential and logarithmic functions. I can also try (but not guarantee) to answer questions on Analysis -- sequences, limits, continuity.

##### Experience in the area

I taught all mathematics subjects from elementary algebra to differential equations at a two-year college in New York City for 25 years.

(See above.)

### Recent Answers from Paul Klarreich

#### 2016-10-28 Related Rates:

Moving cars     Suppose a police officer is 1/2 mile south of an intersection, driving north towards the intersection at 35 mph. At the same time, another car is 1/2 mile east of the intersection, driving

#### 2016-09-17 Velocity and Acceleration:

Questioner:Frances   Country:Hamilton, Bermuda   Category:Calculus   Private:No   Subject:  Mathematics- Differentiation     Question:  A particle moves in a straight line. It's displacement 's' metres

#### 2016-07-20 Compute exponentiation of two complex numbers.:

Let z1 = x1 + i y1    Let z2 = x2 + i y2    If  z =  z1^z2, then    ln(z) = z2 ln(z1)    Now ln(z1) =  ln|z1| + i arg z1    and you can multiply this out with  z2,    then use the fact that    exp(z) =

#### 2016-05-22 Limits and l'Hospital's rule.:

I assume you mean No 8.    This is going to be tricky, and I only have the first part for you.  Perhaps you can use it to push the second part through.    Let  y = (sin x/x)^1/x    ln y = 1/x[ln sin x

#### 2016-03-15 Probability:

Questioner:Akshar   Country:Karnataka, India   Category:Calculus   Private:No   Subject:Probability   Question:Six dice thrown 729 times. How many times do you expect at least one die to show 5 or 6?

Calculus