Home
Class 10
MATHS
Using the Remainder Theorem find the rem...

Using the Remainder Theorem find the remainders obtained when
`x^(3)+(kx+8)x +k` is divided by x + 1 and x - 2.
Hence, find k if the sum of the two remainders is 1.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem using the Remainder Theorem, we will follow these steps: ### Step 1: Define the polynomial Let \( f(x) = x^3 + (kx + 8)x + k \). ### Step 2: Simplify the polynomial First, we can simplify \( f(x) \): \[ f(x) = x^3 + kx^2 + 8x + k \] ### Step 3: Find the remainder when divided by \( x + 1 \) Using the Remainder Theorem, the remainder when \( f(x) \) is divided by \( x + 1 \) is \( f(-1) \): \[ f(-1) = (-1)^3 + k(-1)^2 + 8(-1) + k \] Calculating this gives: \[ f(-1) = -1 + k - 8 + k = 2k - 9 \] Thus, the remainder when \( f(x) \) is divided by \( x + 1 \) is \( 2k - 9 \). ### Step 4: Find the remainder when divided by \( x - 2 \) Now, we find the remainder when \( f(x) \) is divided by \( x - 2 \), which is \( f(2) \): \[ f(2) = (2)^3 + k(2)^2 + 8(2) + k \] Calculating this gives: \[ f(2) = 8 + 4k + 16 + k = 5k + 24 \] Thus, the remainder when \( f(x) \) is divided by \( x - 2 \) is \( 5k + 24 \). ### Step 5: Set up the equation based on the problem statement According to the problem, the sum of the two remainders is 1: \[ (2k - 9) + (5k + 24) = 1 \] Simplifying this equation: \[ 2k - 9 + 5k + 24 = 1 \] \[ 7k + 15 = 1 \] \[ 7k = 1 - 15 \] \[ 7k = -14 \] \[ k = -2 \] ### Conclusion The value of \( k \) is \( -2 \). ---
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • QUESTION PAPER 2019

    ICSE|Exercise SECTION B |20 Videos
  • QUADRATIC EQUATIONS

    ICSE|Exercise Competency Based Questions|10 Videos
  • QUESTION PAPER 2022 TERM 1

    ICSE|Exercise QUESTIONS |33 Videos

Similar Questions

Explore conceptually related problems

Using the Remainder Theorem find the remainders obtained when x^(3)+(kx+8)x+k is divided by x-1andx-2 . Hence find k if the sum of the remainders is 1.

Find the quotient and the remainder (if any), when, 2x^(3) - 8x^(2) + 5x - 8 is divided by x - 2.

Knowledge Check

  • Using remainder theorem, find the remainder when 3x^(4) - 4x^(3) - 3x - 1 is divided by (x - 1).

    A
    1
    B
    -5
    C
    5
    D
    -1
  • Find the remainder when 2 x^(3) - 7 x ^(2) + 5 x - 9 is divided by 2 x - 3

    A
    `-(21)/(2)`
    B
    `-(21)/(4)`
    C
    `-(129)/(4)`
    D
    `-(129)/(2)`
  • The remainder obtained when 3x^(4)+7x^(3)+8x^(2)-2x-3 is divided by x+1 iss

    A
    `-3`
    B
    0
    C
    3
    D
    5
  • Similar Questions

    Explore conceptually related problems

    Find the remainder when x^(3)-ax^(2)+6x-a is divided by x - a

    The remainder when f (x) = x^(2) - 5 x + 8 is divided by x - 1, is

    If the sum of remainders obtained on dividing x^(3) + (k x + 8) x + k by x + 1 and x - 2 is 1 then the value of k is :

    The remainder when f(x) = x^(2) - 4 x + 2 is divided by 2 x + 1 is

    Find the remainder obtained on dividing f(x) = 6 x^(3) - 3 x ^(2) - 8 x + 7 by x - 2