Math Problem Statement

Consider the arithmetic series below. 2+8+14+...... a) Find the value of k where kth term is 332. b) Hence form a quadratic ay^2 +by + c = 0 if the sum of the roots is the term is the tenth term

Solution

The given arithmetic series is: 2+8+14+2 + 8 + 14 + \ldots

a) Finding the value of kk where the kk-th term is 332

In an arithmetic series, the nn-th term ana_n is given by:

an=a1+(n1)da_n = a_1 + (n-1) \cdot d

Where:

  • a1a_1 is the first term,
  • dd is the common difference,
  • nn is the term number.

For the given series:

  • a1=2a_1 = 2
  • The common difference d=82=6d = 8 - 2 = 6

So, the general term formula becomes:

an=2+(n1)6a_n = 2 + (n-1) \cdot 6

We want to find kk such that ak=332a_k = 332:

332=2+(k1)6332 = 2 + (k-1) \cdot 6

Simplifying the equation:

3322=(k1)6332 - 2 = (k-1) \cdot 6 330=(k1)6330 = (k-1) \cdot 6 k1=3306k - 1 = \frac{330}{6} k1=55k - 1 = 55 k=56k = 56

So, the 5656-th term of the arithmetic series is 332.

b) Forming the quadratic equation

We are asked to form a quadratic equation where the sum of the roots is equal to the 1010-th term of the series.

From the formula for the nn-th term: a10=2+(101)6=2+96=2+54=56a_{10} = 2 + (10-1) \cdot 6 = 2 + 9 \cdot 6 = 2 + 54 = 56

So, the sum of the roots of the quadratic equation is 56.

For a quadratic equation ay2+by+c=0ay^2 + by + c = 0, the sum of the roots is given by:

ba=56-\frac{b}{a} = 56

This implies:

b=56ab = -56a

Thus, the quadratic equation will have the form:

ay256ay+c=0ay^2 - 56ay + c = 0

If you have more details for cc, the equation can be fully determined. Otherwise, this is the general form.

Would you like more details on any part of the solution?

Here are some follow-up questions to consider:

  1. How do you derive the general term of an arithmetic sequence?
  2. What is the relationship between the common difference and the sequence terms?
  3. How do you find the sum of the first nn terms of an arithmetic series?
  4. What is the significance of the discriminant in a quadratic equation?
  5. How can you determine the product of the roots from the quadratic equation?

Tip: In quadratic equations, the product of the roots is given by ca\frac{c}{a}, which helps when factoring or solving.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Series
Quadratic Equations

Formulas

n-th term of an arithmetic series: a_n = a_1 + (n-1) * d
Sum of the roots of a quadratic equation: -b/a

Theorems

General formula for the n-th term of an arithmetic sequence
Properties of quadratic equations

Suitable Grade Level

Grades 10-12