You should write the factored form of polynomial such
that:
`x^3 - 2x^2 + 3kx + 18 = (x - 6)(ax^2 + bx +
c)`
You need to open the brackets to the right side such
that:
`x^3 - 2x^2 + 3kx + 18 = ax^3 + bx^2 + cx - 6ax^2 -
6bx - 6c`
You need to collect like terms to the right side
such that:
`x^3 - 2x^2 + 3kx + 18 = ax^3 + x^2(b - 6a) +
x(c - 6b) - 6c`
Equating coefficients of like powers
yields:
`a = 1`
b - 6a = -2
=> b - 6 = -2 => b = 4
`c - 6b = 3k =gt c -
24 = 3k =gt c = 3k + 24`
`-6c = 18 =gt c =
-3`
You need to substitute -3 for c in `c = 3k + 24` such
that:
`-3 = 3k + 24`
Dividing
by 3 both sides yields:
`-1 = k + 8 =gt k =
-9`
Hence, evaluating k using th factored
form of polynomial yields `k = -9` .
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