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If x ^(2)+bx+b is a factor of x ^(3) +2x...

If `x ^(2)+bx+b` is a factor of `x ^(3) +2x ^(2) +2x+c (c ne 0),` then `b-c` is :

A

2

B

`-1`

C

0

D

`-2`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to determine the values of \( b \) and \( c \) given that \( x^2 + bx + b \) is a factor of \( x^3 + 2x^2 + 2x + c \) (where \( c \neq 0 \)). We will do this by performing polynomial long division and finding the conditions under which the remainder is zero. ### Step-by-Step Solution: 1. **Set Up the Division:** We need to divide the cubic polynomial \( x^3 + 2x^2 + 2x + c \) by the quadratic polynomial \( x^2 + bx + b \). 2. **Perform the First Division:** - Divide the leading term of the cubic \( x^3 \) by the leading term of the quadratic \( x^2 \) to get \( x \). - Multiply \( x \) by \( x^2 + bx + b \): \[ x(x^2 + bx + b) = x^3 + bx^2 + bx \] - Subtract this from the original cubic: \[ (x^3 + 2x^2 + 2x + c) - (x^3 + bx^2 + bx) = (2 - b)x^2 + (2 - b)x + c \] 3. **Perform the Second Division:** - Now, divide the leading term \( (2 - b)x^2 \) by \( x^2 \) to get \( 2 - b \). - Multiply \( 2 - b \) by \( x^2 + bx + b \): \[ (2 - b)(x^2 + bx + b) = (2 - b)x^2 + (2 - b)bx + (2 - b)b \] - Subtract this from the previous result: \[ ((2 - b)x^2 + (2 - b)x + c) - ((2 - b)x^2 + (2 - b)bx + (2 - b)b) = (2 - b - (2 - b)b)x + (c - (2 - b)b) \] - This simplifies to: \[ (2 - b)(1 - b)x + (c - (2 - b)b) \] 4. **Set the Remainder to Zero:** For \( x^2 + bx + b \) to be a factor, the remainder must equal zero: - The coefficient of \( x \) must be zero: \[ (2 - b)(1 - b) = 0 \] - This gives us two cases: - Case 1: \( 2 - b = 0 \) → \( b = 2 \) - Case 2: \( 1 - b = 0 \) → \( b = 1 \) 5. **Find Corresponding \( c \):** - For \( b = 2 \): \[ c - (2 - 2) \cdot 2 = 0 \implies c = 0 \quad (\text{not valid since } c \neq 0) \] - For \( b = 1 \): \[ c - (2 - 1) \cdot 1 = 0 \implies c - 1 = 0 \implies c = 1 \] 6. **Calculate \( b - c \):** Now we have \( b = 1 \) and \( c = 1 \): \[ b - c = 1 - 1 = 0 \] ### Final Answer: Thus, the value of \( b - c \) is \( 0 \).
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