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For a polynomial p(x) of degree ge1, p(a...

For a polynomial `p(x)` of degree `ge1, p(a)=0` , where a is a real number, then `(x-a)` is a factor of the polynomial `p(x)`
For what value of k, the polynomial `2x^(4)+3x^(3)+2kx^(2)+3x+6` is exactly divisible by `(x+2)` ?

A

`0`

B

`-1`

C

`1`

D

`2`

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of \( k \) for which the polynomial \( p(x) = 2x^4 + 3x^3 + 2kx^2 + 3x + 6 \) is exactly divisible by \( (x + 2) \), we will use the fact that if \( (x + 2) \) is a factor of \( p(x) \), then \( p(-2) = 0 \). ### Step-by-Step Solution: 1. **Substitute \( x = -2 \) into the polynomial**: \[ p(-2) = 2(-2)^4 + 3(-2)^3 + 2k(-2)^2 + 3(-2) + 6 \] 2. **Calculate each term**: - \( 2(-2)^4 = 2 \times 16 = 32 \) - \( 3(-2)^3 = 3 \times (-8) = -24 \) - \( 2k(-2)^2 = 2k \times 4 = 8k \) - \( 3(-2) = -6 \) - The constant term is \( 6 \). 3. **Combine all the terms**: \[ p(-2) = 32 - 24 + 8k - 6 + 6 \] 4. **Simplify the expression**: \[ p(-2) = 32 - 24 - 6 + 6 + 8k = 32 - 24 = 8 + 8k \] So, we have: \[ p(-2) = 8 + 8k \] 5. **Set the polynomial equal to zero** (since \( p(-2) = 0 \)): \[ 8 + 8k = 0 \] 6. **Solve for \( k \)**: \[ 8k = -8 \implies k = -1 \] ### Final Answer: The value of \( k \) for which the polynomial \( 2x^4 + 3x^3 + 2kx^2 + 3x + 6 \) is exactly divisible by \( (x + 2) \) is \( k = -1 \).
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