Can you present in like a hsc-standard, or be a bit more specific. How did you come up with "a+(b-a)/r2," what is 'r,' so I can know how its between a and b.
r is root. i wanted a + (b-a)/x where x is irrational, x>1, to make rational + irrational = irrational number between a and b. a + (b-a)/r2 = a+r2(b-a)/2 was the choice.
consider the equation as vectors for some intuition, WLOG assume b>a,
a + (b-a)/r2 is a vector between a and b since r2>1.