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Question
Use Remainder theorem to factorize the following polynomial:
`2x^3 + 3x^2 - 9x - 10`
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Solution
Let P(x) = `2x^3 + 3x^2 - 9x - 10`
P(2) = 16 + 12 - 18 - 10
P(2) = 0
So (x - 2) is a factor
Let us divide P(x) with (x-2), we get
`(x- 2)(2x^2 + 7x + 5)`
This can be further factored to
`(x-2)(2x^2 + 5x + 2x + 5)` ……… (Split 7x into two terms, whose sum is 7x and product is10ЁЭСе2)
`(x - 2) (2x^2 + 5x + 2x + 5)`
`(x - 2))(x(2x+5)+1(2x+5))`
(x - 2)(2x + 5)(x + 1)
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