Question
The sum of the first eight terms of a geometric progression. is 510 and the sum of the first four terms of the geometric progression. is $30 .$ Find the first term of the geometric progression., given that it is positive.(A) 2(B) 4(C) 6(D) 8
Step 1
We can write these as two equations: \[ \begin{align*} A + AR + AR^2 + AR^3 + AR^4 + AR^5 + AR^6 + AR^7 &= 510 \tag{1} \\ A + AR + AR^2 + AR^3 &= 30 \tag{2} \end{align*} \] Show more…
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