Explanations
Browse explanation pages that build intuition clearly and then connect the idea to notation, graphs, calculators, and formal reasoning.
What a derivative means geometrically
The derivative is the slope of the tangent line, but that phrase only becomes useful when you compare the curve to nearby secant lines and local linear approximations.
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What an epsilon-delta proof is actually controlling
An epsilon-delta proof is a control problem: keep close enough to a point so the function value stays inside a target band around the limit.
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What eigenvectors and eigenvalues mean geometrically
An eigenvector is a direction that survives a linear transformation without rotating away from its own line. The eigenvalue tells you the scale and possible sign flip along that direction.
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What a -value means and what it does not mean
A -value is a measure of how surprising the observed test statistic would be if the null hypothesis were true. It is not the probability that the null hypothesis itself is true.
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