JAMB - Mathematics (2016 - No. 5)
If the 2nd term of a G.P is \(\frac{8}{9}\) and the 6th term is 4\(\frac{1}{2}\). Find the common ratio.
2
\(\frac{3}{2}\)
\(\frac{2}{3}\)
3
Explanation
T2 = \(\frac{8}{9}\), T6 = 4\(\frac{1}{2}\)
ar = \(\frac{8}{9}\)
ar5 = \(\frac{9}{2}\)
\(\frac{ar}{ar^5}\) = \(\frac{8}{9}\) x \(\frac{2}{9}\)
\(\frac{1}{r^4}\) = \(\frac{16}{81}\)
r = \(\sqrt[4]{\frac{18}{16}}\) = \(\frac{3}{2}\)
ar = \(\frac{8}{9}\)
ar5 = \(\frac{9}{2}\)
\(\frac{ar}{ar^5}\) = \(\frac{8}{9}\) x \(\frac{2}{9}\)
\(\frac{1}{r^4}\) = \(\frac{16}{81}\)
r = \(\sqrt[4]{\frac{18}{16}}\) = \(\frac{3}{2}\)
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