The sum to infinity of a GP is 100, find its first term if the…

Explanation

S\(_∞\) = \(\frac{a}{1- r}\) since 1 > r

S\(_∞\) = 100, r = \(\frac{-1}{2}\), a = ?

100 = \(\frac{a}{1- \frac{-1}{2}}\) = \(\frac{a}{\frac{3}{2}}\) ( - - = +)

a = 100 x \(\frac{3}{2}\) = 150

Therefore, the first term (a) = 150

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