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When x4−px3+2x2−5x+8x^4 - px^3+ 2x^2 -5x + 8x4−px3+2x2−5x+8​ is divided by x -1, the remainder is 2p. The value of p is:
Question

When x4px3+2x25x+8x^4 - px^3+ 2x^2 -5x + 8​ is divided by x -1, the remainder is 2p. The value of p is:

A.

5

B.

3

C.

1

D.

2

Correct option is D

Given:

f(x)=x4px3+2x25x+8f(x) = x^4 - px^3 + 2x^2 - 5x + 8 

and the condition that when this polynomial is divided by x−1, the remainder is 2p.

Concept Used:

The Remainder Theorem states that the remainder when a polynomial f(x) is divided by x − c is f(c).

Solution:

We are given the polynomial

f(x)=x4px3+2x25x+8f(x) = x^4 - px^3 + 2x^2 - 5x + 8 ​

As, the divisor is (x−1)

Substituting x = 1 into f(x):

f(1)=(1)4p(1)3+2(1)25(1)+8f(1) = (1)^4 - p(1)^3 + 2(1)^2 - 5(1) + 8​​

f(1)=1p+25+8f(1) = 1 − p + 2 − 5 + 8

f(1)=6pf(1)=6−p 

Remainder when dividing by (x−1) is 2p, so:

f(1)=2pf(1)=2p 

6p=2p6−p=2p

3p = 6 

p = 2

Thus, the value of p is 2.

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