Q4 of 108 Page 38

On dividing the polynomial f(x) = x3 – 3x2 + x + 2 by the polynomial g(x), quotient q(x) and remainder f(x) are respectively obtained as x – 2 and –2x + 4. Find the polynomial g(x).

Given:

Dividend = f(x) = x3 – 3x2 + x + 2


Divisor = g(x)


Quotient = x – 2


Remainder = -2x + 4


There is an important relation between dividend, divisor, quotient and remainder which is as follows:


Dividend = Divisor × Quotient + Remainder


x3 – 3x2 + x + 2 = g(x) × (x-2) + (4-2x)


g(x) × (x-2) = x3 – 3x2 + x + 2 – (4 – 2x)


= x3 – 3x2 + x + 2 – 4 + 2x


g(x) × (x-2) = x3 – 3x2 + 3x – 2


Therefore g(x) = (x3 – 3x2 + 3x – 2) / (x-2)



Therefore the g(x) = x2 – x – 1


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