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XAT 2014 — QA & DI Question 5

Simple EquationsEasy

A polynomial “ax3 + bx2 + cx + d” intersects x-axis at 1 and –1, and y-axis at 2. The value of b is:

Answer & solution

Correct answer: -2

  • -2

  • B

    0

  • C

    1

  • D

    2

  • E

    Cannot be determined

Solution

ax3 + bx2 + cx + d intersects x axis at 1 & –1

∴ a + b + c + d = 0

–a + b – c + d = 0

∴ 2(b + d) = 0

∴ b + d = 0

ax3 + bx2 + cx + d intersects y axis at 2

0 + d = 2

∴ d = 2

From (1) & (2), b = –2

Hence, option (a).

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XAT 2014 QA & DI Q5: A polynomial “ ax 3 + bx 2 + cx + d ” intersects x -axis at 1 and –1, and y -axis at 2. The — Solution | TheCATExam