Q. 45.0( 3 Votes )

The polynomials x

Answer :

Let p(x) = x3 + x2 – 4x + a and q(x) = 2x3 + ax2 + 3x – 3


We have to find remainders when p(x) is divided by x – 2 and when q(x) is divided by x – 2 and equate them as it is given that both are equal


Now we will find remainder using remainder theorem which states that


If a polynomial t(x) is divided by a polynomial x – b then the remainder is t(b)


Compare x – 2 with x – b we have b = 2


Let us first find remainder when p(x) is divided by x – 2


Substitute 2 in p(x)


p(2) = 23 + 22 – 4(2) + a


p(2) = 8 + 4 – 8 + a


p(2) = 4 + a …(i)


Now let us find remainder when q(x) is divided by x – 2


Substitute 2 in q(x)


q(2) = 2(2)3 + a(2)2 + 3(2) – 3


q(2) = 2(8) + 4a + 6 – 3


q(2) = 16 + 4a + 3


q(2) = 19 + 4a …(ii)


Equate (i) and (ii)


4 + a = 19 + 4a


4a – a = 4 - 19


3a = - 15


a = - 5


Hence value of a is - 5


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