Let` a/b = b/c =k.` Then, `b = ck and a = bk = ck^2` `:. a^4/b^4 = (c^4 k^8)/(c^4 k^4)` `= k^4 and a^2/c^2 = (c^2 k^4)/c^2 = k^4` Hence,` a^4/b^4` `= a^2/c^2`