Original question was to write the fraction in its simplest form:
Question: 4r/[(√6r) + 9]
I attempted to solve it by multiplying the denominator and numerator by the conjugates of the denominator, ((√6r) - 9).
numerator: [4r*(√6r)] - 36r denominator: 6r2 - 81
numerator: [4r2*(√6)] - 36r denominator: 6r2 -81
Why was the r under the √6r removed in the numerator?
Why and how did 4r become 4r2?