Question Details

If the polynomial ( 2x3 + ax2 + 3x 5 ) and ( x3 + x2 2x + a ) leave the same remainder when divided by ( x 2 ) , find the remainder.

Options

A

5

B

2

C

3

D

4

Show Answer

Correct Answer :

Option A

5

Solution :

The correct answer is 5.

Step-by-step Explanation:

Let the two given polynomials be:
P ( x ) = 2 x 3 + a x 2 + 3 x - 5
and
Q ( x ) = x 3 + x 2 - 2 x + a

According to the Remainder Theorem, when a polynomial f(x) is divided by ( x - c ) , the remainder is f(c).
Here, both polynomials are divided by ( x - 2 ) . Therefore, the remainders are P ( 2 ) and Q ( 2 ) respectively.

Since it is given that both polynomials leave the same remainder:
P ( 2 ) = Q ( 2 )

First, let's find the value of P ( 2 ) by substituting x = 2 into P(x):
P ( 2 ) = 2 ( 2 ) 3 + a ( 2 ) 2 + 3 ( 2 ) - 5
P ( 2 ) = 2 ( 8 ) + 4 a + 6 - 5
P ( 2 ) = 16 + 4 a + 1
P ( 2 ) = 17 + 4 a

Next, let's find the value of Q ( 2 ) by substituting x = 2 into Q(x):
Q ( 2 ) = ( 2 ) 3 + ( 2 ) 2 - 2 ( 2 ) + a
Q ( 2 ) = 8 + 4 - 4 + a
Q ( 2 ) = 8 + a

Equating the two expressions for the remainders:
17 + 4 a = 8 + a

Subtract a from both sides:
17 + 3 a = 8

Subtract 17 from both sides:
3 a = 8 - 17
3 a = - 9
a = - 3

Now, substitute the value of a back into either remainder expression to find the final remainder value:
Remainder = 8 + a
Remainder = 8 + ( - 3 ) = 5

Thus, the remainder is 5.

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