1(ii)
What must be subtracted from the polynomial x3 + x2 - 2x + 1, so that the result is exactly divisible by (x - 3)?
- (a)–31
- (b)–30
- (c)30
- (d)31
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Polynomial : x3 + x2 - 2x + 1
Division by x - 3
⇒ x - 3 = 0
⇒ x = 3.
Let k be subtracted from the polynomial, so resulting polynomial is x3 + x2 - 2x + 1 - k.
Resulting polynomial should be exactly divisible by x - 3,
Thus, substituting x = 3, in polynomial x3 + x2 - 2x + 1 - k, remainder = 0.
⇒ 33 + 32 - 2(3) + 1 - k = 0
⇒ 27 + 9 - 6 + 1 - k = 0
⇒ 31 - k = 0
⇒ k = 31.
Hence, Option 4 is the correct option.