Math Problem Statement
Solution
The image contains two math problems involving geometric progressions (GP). I'll break down each one:
Question 1:
"Given are the first three positive terms of a GP, calculate the sum of the first 6 terms."
We are given three terms of a geometric progression (GP). In a GP, the ratio between consecutive terms is constant, so we can use that information to find the value of and then calculate the sum of the first 6 terms.
Step-by-Step Approach:
- Set up the GP ratio:
For a GP, the ratio between the second and first term is the same as the ratio between the third and second term.
So,
- Solve for : Cross-multiply and simplify to find .
- Find the common ratio: Once is determined, substitute it back to find the common ratio .
- Sum formula: The sum of the first terms of a GP is given by: where is the first term, is the common ratio, and is the number of terms. Use this to find the sum of the first 6 terms.
Question 2:
"The sum of the first 4 terms of a GP is 60. Its third term exceeds the first term by 8. If the first term is greater than 1, calculate the sum of the first 6 terms."
Here, we need to calculate the sum of the first 6 terms, given:
- The sum of the first 4 terms is 60.
- The third term exceeds the first by 8.
- The first term is greater than 1.
Step-by-Step Approach:
- Set up equations: Let the first term be and the common ratio be . The four terms are: The sum of the first 4 terms is: The condition that the third term exceeds the first by 8 gives:
- Solve for and : Use these two equations to solve for and .
- Find the sum of the first 6 terms: After determining and , use the formula for the sum of the first 6 terms of a GP.
Let me know if you would like me to solve these problems fully or provide any further clarifications.
Five Related Questions:
- How do we determine the common ratio in a geometric progression?
- What is the difference between arithmetic and geometric progressions?
- How do you find the sum of an infinite geometric series?
- What happens if the common ratio is negative in a geometric progression?
- How do we derive the formula for the sum of the first terms of a GP?
Tip:
Always cross-check if your sequence is a valid GP by ensuring the ratio between consecutive terms remains constant.
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Math Problem Analysis
Mathematical Concepts
Geometric Progression (GP)
Ratios
Equations
Formulas
Common ratio formula: r = term_n / term_(n-1)
Sum of the first n terms of a GP: S_n = a(1 - r^n) / (1 - r)
Theorems
Properties of Geometric Progression
Suitable Grade Level
Grades 10-12