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# Monthly Archives: September 2016

#### Holding the other parts constant: it’s everywhere!

It seems like ages ago — but it was only yesterday — that I wrote about differentiating functions with the variable in both the base and the power. Back there, I had learned that the derivative of a function like f(x)g(x) is the sum of the derivative when you pretend f(x) is constant and the […]

#### The Zumbo (hypothesis) Test

Here in Australia, we are at the tail end of a reality cooking competition called “Zumbo’s Just Desserts“. In the show, a group of hopefuls compete in challenges where they produce desserts, hosted by patissier Adriano Zumbo. There are two types of challenges. In the “Sweet Sensations” challenge, they have to create a dessert from […]

#### Problem strings and using the chain rule with functions defined as integrals

In Maths 1A here at the University of Adelaide, they learn the following theorem (this is taken from the lecture notes written by the School of Maths here):

It says that, given a function of x defined as the integral of an original function from a constant to x, when you differentiate it you get the […]

#### Differentiating exponents: two wrongs make a right

I was talking to a student about his calculus last week. He was trying to differentiate xx. (Actually he was trying to differentiate x ln(x) and had decided the best place to start was to raise e to the power of it, thus producing xx.) At first he tried this:

I asked him what he thought […]

#### SQWIGLES: a guide for action and reflection in one-on-one teaching

It’s university holidays again (aka “non-lecture time”), which means I’m back on the blog trying to process everything that’s happened this term. Mostly this has been me spending time with students in the Drop-In Centre, since I made a commitment to do more of what I love, which is spending time with students in the […]

#### (Holding it together)

Last week, I helped quite a few students from International Financial Institutions and Markets with their annuity calculations, which involve quite detailed stuff like this:

There were several small issues a lot of them had, which combined to stall their calculations. One of the more important problems was about how the calculator interprets what they type […]