Question:

Let the first term $a$ and common ratio $r$ of a GP be positive integers. If sum of squares of first 3 terms is 33033, then sum of first 3 terms is

210

231

200

220

Step-by-Step Solution

Key Concept: $a^2(1+r^2+r^4)=33033=11^2\cdot3\cdot7\cdot13=11^2\cdot273$. So $a=11$, $1+r^2+r^4=273\Rightarrow r=4$.

$a=11,r=4$. Sum $=231$.

Correct Answer: 2