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{:("If",a = 1 + 2 + 4 + ..."to n terms")...

`{:("If",a = 1 + 2 + 4 + ..."to n terms"),(,b = 1 + 3 + 9 + ..."to n terms"),(,c =1 + 5 + 25+ ..."to n terms"):}`
then `|(a,2b,4c),(2,2,2),(2^(n),3^(n),5^(n))|=`

A

`(30)^(n)`

B

`(10)^(n)`

C

`0`

D

`2^(n)+3^(n)+5^(n)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we need to find the determinant of the matrix formed by the expressions for \(a\), \(b\), and \(c\). Let's break this down step by step. ### Step 1: Identify the sums \(a\), \(b\), and \(c\) 1. **Sum \(a\)**: \[ a = 1 + 2 + 4 + \ldots \text{ (to n terms)} \] This is a geometric series with the first term \(1\) and common ratio \(2\). The sum of the first \(n\) terms of a geometric series is given by: \[ S_n = \frac{a(r^n - 1)}{r - 1} \] Here, \(a = 1\), \(r = 2\), and \(n\) is the number of terms. Thus: \[ a = \frac{1(2^n - 1)}{2 - 1} = 2^n - 1 \] 2. **Sum \(b\)**: \[ b = 1 + 3 + 9 + \ldots \text{ (to n terms)} \] This is also a geometric series with first term \(1\) and common ratio \(3\). Therefore: \[ b = \frac{1(3^n - 1)}{3 - 1} = \frac{3^n - 1}{2} \] 3. **Sum \(c\)**: \[ c = 1 + 5 + 25 + \ldots \text{ (to n terms)} \] This is a geometric series with first term \(1\) and common ratio \(5\). Thus: \[ c = \frac{1(5^n - 1)}{5 - 1} = \frac{5^n - 1}{4} \] ### Step 2: Substitute \(a\), \(b\), and \(c\) into the determinant Now we can substitute \(a\), \(b\), and \(c\) into the determinant: \[ \begin{vmatrix} a & 2b & 4c \\ 2 & 2 & 2 \\ 2^n & 3^n & 5^n \end{vmatrix} = \begin{vmatrix} (2^n - 1) & 2 \cdot \frac{3^n - 1}{2} & 4 \cdot \frac{5^n - 1}{4} \\ 2 & 2 & 2 \\ 2^n & 3^n & 5^n \end{vmatrix} \] This simplifies to: \[ \begin{vmatrix} (2^n - 1) & (3^n - 1) & (5^n - 1) \\ 2 & 2 & 2 \\ 2^n & 3^n & 5^n \end{vmatrix} \] ### Step 3: Apply row operations We can apply row operations to simplify the determinant. Let's perform the following operations: - Replace \(R_2\) with \(R_2 - R_1\) (subtract the first row from the second row). - Replace \(R_1\) with \(R_1\) divided by \(2\). This gives us: \[ \begin{vmatrix} (2^n - 1) & (3^n - 1) & (5^n - 1) \\ 0 & 0 & 0 \\ 2^n & 3^n & 5^n \end{vmatrix} \] ### Step 4: Evaluate the determinant Since the second row consists entirely of zeros, the determinant of this matrix is: \[ \text{Determinant} = 0 \] ### Conclusion Thus, the value of the determinant is: \[ \boxed{0} \]

To solve the given problem, we need to find the determinant of the matrix formed by the expressions for \(a\), \(b\), and \(c\). Let's break this down step by step. ### Step 1: Identify the sums \(a\), \(b\), and \(c\) 1. **Sum \(a\)**: \[ a = 1 + 2 + 4 + \ldots \text{ (to n terms)} \] ...
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