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The second term of an infinte geometric ...

The second term of an infinte geometric progression is 2 and its sum to infinity is 8. The first term is

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To find the first term of the infinite geometric progression (GP), we will follow these steps: ### Step 1: Understand the properties of the geometric progression In a geometric progression, the terms can be expressed as: - First term: \( a \) - Second term: \( ar \) - Third term: \( ar^2 \) - And so on... ### Step 2: Set up the equations based on the problem We are given: 1. The second term \( ar = 2 \) 2. The sum to infinity \( S = \frac{a}{1 - r} = 8 \) ### Step 3: Solve for \( r \) from the second term From the first equation, we can express \( r \) in terms of \( a \): \[ ar = 2 \implies r = \frac{2}{a} \] ### Step 4: Substitute \( r \) into the sum to infinity formula Now, substitute \( r \) into the sum to infinity formula: \[ S = \frac{a}{1 - r} = 8 \] Substituting \( r = \frac{2}{a} \): \[ \frac{a}{1 - \frac{2}{a}} = 8 \] ### Step 5: Simplify the equation To simplify the equation: \[ \frac{a}{\frac{a - 2}{a}} = 8 \implies \frac{a^2}{a - 2} = 8 \] ### Step 6: Cross-multiply to eliminate the fraction Cross-multiplying gives: \[ a^2 = 8(a - 2) \] ### Step 7: Expand and rearrange the equation Expanding the right side: \[ a^2 = 8a - 16 \] Rearranging gives: \[ a^2 - 8a + 16 = 0 \] ### Step 8: Factor the quadratic equation This can be factored as: \[ (a - 4)^2 = 0 \] ### Step 9: Solve for \( a \) Setting the factor equal to zero gives: \[ a - 4 = 0 \implies a = 4 \] ### Conclusion The first term \( a \) of the infinite geometric progression is \( 4 \). ---
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