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If p and q(ne0) are the roots of the equ...

If `p and q(ne0)` are the roots of the equation `x^(2)+px+q=0`, then the value of p must be equal to

A

a. 0, 1

B

c. `(1)/(4)`

C

b. 0

D

d. 2, 0

Text Solution

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The correct Answer is:
To solve the problem, we need to find the value of \( p \) given that \( p \) and \( q \) (where \( q \neq 0 \)) are the roots of the quadratic equation \( x^2 + px + q = 0 \). ### Step-by-Step Solution: 1. **Identify the coefficients**: The given quadratic equation is \( x^2 + px + q = 0 \). Here, we can identify the coefficients: - \( a = 1 \) (coefficient of \( x^2 \)) - \( b = p \) (coefficient of \( x \)) - \( c = q \) (constant term) 2. **Sum of the roots**: The sum of the roots of a quadratic equation \( ax^2 + bx + c = 0 \) is given by the formula: \[ \text{Sum of roots} = -\frac{b}{a} \] Substituting the values, we have: \[ p + q = -\frac{p}{1} = -p \] Rearranging this gives: \[ p + q = -p \implies q = -2p \quad \text{(Equation 1)} \] 3. **Substituting one root into the equation**: Since \( p \) is a root of the equation \( x^2 + px + q = 0 \), we substitute \( x = p \): \[ p^2 + p \cdot p + q = 0 \] This simplifies to: \[ p^2 + p^2 + q = 0 \implies 2p^2 + q = 0 \] 4. **Substituting \( q \) from Equation 1**: Now, we substitute \( q = -2p \) from Equation 1 into the equation \( 2p^2 + q = 0 \): \[ 2p^2 - 2p = 0 \] 5. **Factoring the equation**: We can factor out \( 2p \): \[ 2p(p - 1) = 0 \] This gives us two possible solutions: \[ 2p = 0 \quad \text{or} \quad p - 1 = 0 \] 6. **Finding the values of \( p \)**: From \( 2p = 0 \): \[ p = 0 \] From \( p - 1 = 0 \): \[ p = 1 \] 7. **Conclusion**: Thus, the possible values of \( p \) are: \[ p = 0 \quad \text{or} \quad p = 1 \] ### Final Answer: The values of \( p \) must be equal to \( 0 \) and \( 1 \). ---
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Knowledge Check

  • If p, q are the roots of the equation x^(2)+px +q=0 , then

    A
    p = 1, q = -2
    B
    p = 0, q = 1
    C
    p = -2, q = 0
    D
    p = -2, q = 1
  • If p and q are the roots of the equation x^2+px+q=0 , then :

    A
    p = 1 or 0
    B
    p = -2 or 0
    C
    p = -2
    D
    p = 1
  • If p and q are the roots of the equation x^2+px+q=0 , then :

    A
    p = 1 or 0
    B
    p = -2 or 0
    C
    p = -2
    D
    p = 1
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