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The polynomial px^(3)+4x^(2)-3x+q comple...

The polynomial `px^(3)+4x^(2)-3x+q` completely divisible by `x^2-1:` find the values of p and q. Also for these values of p and q factorize the given polynomial completely.

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To solve the problem, we need to find the values of \( p \) and \( q \) such that the polynomial \( f(x) = px^3 + 4x^2 - 3x + q \) is completely divisible by \( x^2 - 1 \). ### Step 1: Understand the Divisibility Condition Since \( f(x) \) is divisible by \( x^2 - 1 \), it means that \( f(x) \) has roots at \( x = 1 \) and \( x = -1 \). Therefore, \( f(1) = 0 \) and \( f(-1) = 0 \). ### Step 2: Calculate \( f(-1) \) Substituting \( x = -1 \) into the polynomial: \[ f(-1) = p(-1)^3 + 4(-1)^2 - 3(-1) + q \] This simplifies to: \[ f(-1) = -p + 4 + 3 + q = -p + q + 7 \] Since \( f(-1) = 0 \): \[ -p + q + 7 = 0 \quad \text{(Equation 1)} \] ### Step 3: Calculate \( f(1) \) Now substituting \( x = 1 \) into the polynomial: \[ f(1) = p(1)^3 + 4(1)^2 - 3(1) + q \] This simplifies to: \[ f(1) = p + 4 - 3 + q = p + q + 1 \] Since \( f(1) = 0 \): \[ p + q + 1 = 0 \quad \text{(Equation 2)} \] ### Step 4: Solve the System of Equations Now we have two equations: 1. \( -p + q + 7 = 0 \) 2. \( p + q + 1 = 0 \) From Equation 2, we can express \( q \) in terms of \( p \): \[ q = -p - 1 \quad \text{(Substituting into Equation 1)} \] Substituting \( q \) into Equation 1: \[ -p + (-p - 1) + 7 = 0 \] This simplifies to: \[ -2p + 6 = 0 \] Solving for \( p \): \[ 2p = 6 \implies p = 3 \] ### Step 5: Find \( q \) Now substituting \( p = 3 \) back into the expression for \( q \): \[ q = -3 - 1 = -4 \] ### Step 6: Final Values Thus, we have: \[ p = 3, \quad q = -4 \] ### Step 7: Factor the Polynomial Now substituting \( p \) and \( q \) back into the polynomial: \[ f(x) = 3x^3 + 4x^2 - 3x - 4 \] To factor \( f(x) \), we can use polynomial long division with the divisor \( x^2 - 1 \): 1. Divide \( 3x^3 \) by \( x^2 \) to get \( 3x \). 2. Multiply \( 3x \) by \( x^2 - 1 \) to get \( 3x^3 - 3x \). 3. Subtract this from \( f(x) \): \[ (3x^3 + 4x^2 - 3x - 4) - (3x^3 - 3x) = 4x^2 - 4 \] 4. Now divide \( 4x^2 \) by \( x^2 \) to get \( 4 \). 5. Multiply \( 4 \) by \( x^2 - 1 \) to get \( 4x^2 - 4 \). 6. Subtract this from the previous result: \[ (4x^2 - 4) - (4x^2 - 4) = 0 \] Thus, we have: \[ f(x) = (x^2 - 1)(3x + 4) \] ### Final Factorization The complete factorization of the polynomial is: \[ f(x) = (x + 1)(x - 1)(3x + 4) \]
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