Hello,

If $\displaystyle \frac{a}{b} = \frac{b}{c} = \frac{c}{d}, $ prove that

$\displaystyle \frac{a}{d} $ is equal to $\displaystyle \sqrt{\frac{a^5 + b^2c^2 + a^3c^2}{b^4c + d^4 + b^2cd^2}} $

It seems like a mess. Any suggestions on where to start?

Btw, this problem is from Higher Algebra by H.S Hall and S. R Knight, a textbook that is still used in India even though it was written in the 1800's.