## Excel: How to make a graph from data and get an equation, 4 easy steps

The tutor shares quick, easy way to get a graph and equation from Excel, 2007 version. Let’s imagine your x data is in range a1:a10, your y-data, b1:b10. Select a1:b10, then click Insert, then the Scatter icon. Then, in the …

## Calculator Usage: changing the cells of the TI-30XA

The tutor shares a bit of calculator maintenance. The TI-30XA uses two cells. The ones I took out of mine say GPA76. I replaced them with AG13 cells; the calculator seems to work fine. The back of the TI-30XA has …

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## Spreadsheets: regression curves: power vs exponential

The tutor explains the difference between power and exponential curves. According to Excel, a power equation has the form y=axb whereas an exponential equation has the form y=aekx Example: I tried both options on the following data: x y 0.5 …

## Spreadsheets: Excel: the logest() function

The tutor shows how to use the logest() function to get an exponential curve from data. Excel’s logest() function returns parameters for the equation y=bm^x, according to data fed for x and y values. Let’s imagine the data is as …

## Web design: z-index: one way to superpose content

The tutor shows a way to place content over other content. To put content on top of other content, the z-index style parameter can be used. If two elements are set at the same absolute position, the one with the …

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## Web Programming: JavaScript: how to manage a multi-line string

The tutor tells a trick for printing long strings with JavaScript. Suppose you have a long string, over many lines, that you want to print with JavaScript. Typically, to print a string, you might assign it to a variable, then …

## Web design: a JavaScript wrapper for SVG in WordPress

The tutor shows an example of a wrapper program in action. To my knowledge, a wrapper is a program that hides a function that the managing system can’t handle. The “wrapping” is code that the managing system recognizes as the …

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## Linear algebra: matrix multiplication: no cancellation rule

The tutor gives an example to show that with matrices, AB=AC doesn’t mean B=C. Consider the matrices A, B, C, and D: By matrix multiplication, AB=AC. (In fact, both products equal D.) Yet, obviously, B≠C. Matrix multiplication lacks the cancellation …

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## Calculus: concavity and point of inflection

The tutor explains concavity and point of inflection with an example. Concavity refers to an aspect of graph shape. My first-year calculus professor explained it this way: concave upward will collect rain, while concave downward will shed rain. Numerically, when …