## Posts tagged proof

### Visualizing the Pythagorean Theorem

Most people are familiar with the Pythagorean theorem: In a right-angled triangle the square of the hypotenuse is equal to the sum of the squares of the other two sides. As the name of the theorem implies, it is attributed to Pythagoras, a Greek mathematician who lived around 500 B.C. The theorem is also included [...]

### On the Divergence of a Geometric Progression Sum

Let us revisit the geometric progression sum considered in an earlier article,

$s_r = \sum_{k=0}^\infty r^k = 1 + r + r^2 + r^3 + \ldots,$

where $r$ here is a complex number. For what values of $r$ does this infinite sum make sense? Can we find a closed-form expression for $s_r$ in such cases?

### Nice Proof of a Geometric Progression Sum

Consider the geometric series,
$s_r = \sum_{k=0}^\infty r^k = 1 + r + r^2 + r^3 + \ldots,$
for $0 < r < 1$. The goal is to find a closed-form expression for $s_r$ [...]