JIPMAT 2023 (QA) - <p>The expression 2x<sup>3</sup> + ax<sup>2</sup> + bx + 3, where a and b are constants, has a factor of x-1 and leaves a remainder of 15 when divided by x + 2. Then, (a, b) =</p> | PYQs + Solutions | AfterBoards
Skip to main contentSkip to question navigationSkip to solution
IPMAT Indore Free Mocks Topic Tests

JIPMAT 2023 (QA) PYQs

JIPMAT 2023

Number System
>
Miscellaneous

Easy

The expression 2x3 + ax2 + bx + 3, where a and b are constants, has a factor of x-1 and leaves a remainder of 15 when divided by x + 2. Then, (a, b) =

Correct Option: 2
1) The expression: 2x3+ax2+bx+32x^3 + ax^2 + bx + 3
2) Since x1x-1 is a factor, the expression should be equal to 00 when x=1x=1\newline - When x=1x=1: \newline2(1)3+a(1)2+b(1)+3=02(1)^3 + a(1)^2 + b(1) + 3 = 0\newline - Simplifies to: 2+a+b+3=02 + a + b + 3 = 0\newline - Therefore: a+b=5a + b = -5 ...(1)
3) When divided by x+2x+2, remainder is 1515\newline - When x=2x=-2: \newline2(2)3+a(2)2+b(2)+3=152(-2)^3 + a(-2)^2 + b(-2) + 3 = 15\newline - 16+4a2b+3=15-16 + 4a - 2b + 3 = 15\newline - 4a2b=284a - 2b = 28 ...(2)\newline - 2ab=142a - b = 14
4) We now have two equations:\newline - a+b=5a + b = -5 ...(1)\newline - 2ab=142a - b = 14 ...(2)
5) From (1): b=5ab = -5 - a\newline Substitute in (2):\newline - 2a(5a)=142a - (-5-a) = 14\newline - 2a+5+a=142a + 5 + a = 14\newline - 3a=93a = 9\newline - a=3a = 3
6) Put back to find bb:\newline - b=53=8b = -5 - 3 = -8
Therefore, (a,b)=(3,8)(a,b) = (3,-8)

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question