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If p(x+1)^(2) +q(x^(2)-3x-2)+x+1=0 be an...

If `p(x+1)^(2) +q(x^(2)-3x-2)+x+1=0` be an identity in x, then p,q are

A

2,-2

B

1,-1

C

0,0

D

none

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The correct Answer is:
To solve the equation \( p(x+1)^2 + q(x^2 - 3x - 2) + x + 1 = 0 \) as an identity in \( x \), we need to ensure that the coefficients of the polynomial are zero for all powers of \( x \). This means we need to collect like terms and set the coefficients of \( x^2 \), \( x \), and the constant term to zero. ### Step 1: Expand the equation First, we expand \( p(x+1)^2 \) and \( q(x^2 - 3x - 2) \): \[ p(x+1)^2 = p(x^2 + 2x + 1) = px^2 + 2px + p \] \[ q(x^2 - 3x - 2) = qx^2 - 3qx - 2q \] Now, substituting these back into the original equation: \[ px^2 + 2px + p + qx^2 - 3qx - 2q + x + 1 = 0 \] ### Step 2: Combine like terms Next, we combine the terms: \[ (px^2 + qx^2) + (2px - 3qx + x) + (p - 2q + 1) = 0 \] This simplifies to: \[ (p + q)x^2 + (2p - 3q + 1)x + (p - 2q + 1) = 0 \] ### Step 3: Set coefficients to zero For the equation to be an identity, the coefficients of \( x^2 \), \( x \), and the constant term must all be zero: 1. \( p + q = 0 \) (Coefficient of \( x^2 \)) 2. \( 2p - 3q + 1 = 0 \) (Coefficient of \( x \)) 3. \( p - 2q + 1 = 0 \) (Constant term) ### Step 4: Solve the equations From the first equation, we can express \( q \) in terms of \( p \): \[ q = -p \] Now substitute \( q = -p \) into the second equation: \[ 2p - 3(-p) + 1 = 0 \implies 2p + 3p + 1 = 0 \implies 5p + 1 = 0 \implies p = -\frac{1}{5} \] Now substitute \( p = -\frac{1}{5} \) back into \( q = -p \): \[ q = -(-\frac{1}{5}) = \frac{1}{5} \] ### Step 5: Final values Thus, we find: \[ p = -\frac{1}{5}, \quad q = \frac{1}{5} \] ### Summary The values of \( p \) and \( q \) are: \[ p = -\frac{1}{5}, \quad q = \frac{1}{5} \]
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ML KHANNA-THEORY OF QUADRATIC EQUATIONS -Self Assessment Test
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  7. Let alpha and beta are the roots of the equation x^(2) + x + 1 = 0 The...

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  8. If the quadratic equation x^(2) +ax +b =0 and x^(2) +bx +a =0 (a ne b...

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  15. If alpha and beta (alpha lt beta) are the roots of the equation x^(2) ...

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  16. If 2a+3b+6c=0, then prove that at least one root of the equation a x^2...

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  20. The value of a for which one root of the quadratic equation (a^2-5a+3)...

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  21. If a,b, c are in G.P., then the equations ax^(2) + 2bx + c = 0 and dx^...

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