### Janusz Asked

In y = ax +b when are a, -b/a, b in arithmetic progression. The polynomial y = ax^2 + bx + c has roots r1 and r2. Can a, r1, b, r2 and c be in arithmetic progression?

### Roots and Coefficients

If xyz = 1 and x+y+z =1/x + 1/y + 1/z show that at least one of these numbers must be 1. Now for the complexity! When are the other numbers real and when are they complex?

### Agile Algebra

Observe symmetries and engage the power of substitution to solve complicated equations.

# Fibonacci Fashion

##### Stage: 5 Challenge Level:

$F_n={1\over\sqrt5}(\alpha^n-\beta^n)$ where $\alpha$ and $\beta$ are solutions of the quadratic equation $x^2-x-1=0$ and $\alpha > \beta$ is the explicit formula for the $n$th Fibonacci number as given in this question.

The Golden Ratio is one of the roots of the quadratic equation and this explains the many connections between Fibonacci numbers and the Golden Ratio.

This problem complements the material in the article The Golden Ratio, Fibonacci Numbers and Continued Fractions
For a sequence of, mainly more elementary, problems on these topics see
Golden Mathematics

See this article if you want to know more about the method of proof by mathematical induction.