When the function q(x) = x3 + kx2 – 7x + 3 is divided by (x + 1) the remainder is seven times theremainder that is found when the function is divided by (x + 2).Find the value of k
Question
When the function q(x) = x3 + kx2 – 7x + 3 is divided by (x + 1) the remainder is seven times theremainder that is found when the function is divided by (x + 2).Find the value of k
Solution
To solve this problem, we will use the Remainder Theorem which states that the remainder of a polynomial f(x) divided by (x-a) is f(a).
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According to the problem, when q(x) is divided by (x + 1), the remainder is 7 times the remainder when q(x) is divided by (x + 2). So, we can write this as: q(-1) = 7q(-2).
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Substituting x = -1 and x = -2 into the function q(x) = x^3 + kx^2 - 7x + 3, we get:
q(-1) = (-1)^3 + k(-1)^2 - 7(-1) + 3 = -1 + k + 7 + 3 = k + 9
q(-2) = (-2)^3 + k(-2)^2 - 7(-2) + 3 = -8 + 4k + 14 + 3 = 4k + 9
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Now, substitute q(-1) and q(-2) into the equation q(-1) = 7q(-2) to get:
k + 9 = 7(4k + 9)
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Simplify the equation to solve for k:
k + 9 = 28k + 63
27k = -54
k = -54 / 27
k = -2
So, the value of k is -2.
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