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If alpha and 1/alpha are the zeroes of t...

If `alpha` and `1/alpha` are the zeroes of the polynomial `4x^2-2x+(k-4)`, then value of k is:

A

4

B

8

C

0

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of \( k \) for the polynomial \( 4x^2 - 2x + (k - 4) \) given that \( \alpha \) and \( \frac{1}{\alpha} \) are its zeroes, we can follow these steps: ### Step 1: Identify the coefficients of the polynomial The polynomial is given as: \[ 4x^2 - 2x + (k - 4) \] Here, the coefficients are: - \( a = 4 \) - \( b = -2 \) - \( c = k - 4 \) ### Step 2: Use the properties of the roots For a quadratic polynomial \( ax^2 + bx + c \), if \( \alpha \) and \( \beta \) are the roots, then: 1. The sum of the roots \( \alpha + \beta = -\frac{b}{a} \) 2. The product of the roots \( \alpha \cdot \beta = \frac{c}{a} \) In our case, the roots are \( \alpha \) and \( \frac{1}{\alpha} \). ### Step 3: Calculate the sum of the roots The sum of the roots is: \[ \alpha + \frac{1}{\alpha} = -\frac{-2}{4} = \frac{2}{4} = \frac{1}{2} \] ### Step 4: Calculate the product of the roots The product of the roots is: \[ \alpha \cdot \frac{1}{\alpha} = 1 = \frac{k - 4}{4} \] ### Step 5: Set up the equation for the product of the roots From the product of the roots, we have: \[ 1 = \frac{k - 4}{4} \] ### Step 6: Solve for \( k \) To solve for \( k \), multiply both sides by 4: \[ 4 = k - 4 \] Now, add 4 to both sides: \[ k = 4 + 4 = 8 \] ### Final Answer The value of \( k \) is: \[ \boxed{8} \]
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