JAMB - Mathematics (1998 - No. 8)

When the expression pm\(^2\) + qm + 1 is divided by (m - 1), it has a remainder is 2, and when divided by (m + 1), the remainder is 4. Find p and q respectively
2, -1
-1, 2
3, -2
-2, 3

Explanation

pm\(^2\) + qm + 1 = (m - 1) Q(x) + 2, where Q(x) = remainder.

p(1)\(^2\) + q(1) + 1 = 2

p + q + 1 = 2

p + q = 1.....(i)

pm\(^2\) + qm + 1 = (m - 1)Q(x) + 4

p(-1)\(^2\) + q(-1) + 1 = 4

p - q + 1 = 4

p - q = 3....(ii)

p + q = 1, p - q = 3

Using elimination method, add eqn i and ii

2p = 4, p = 2

from eqn ii

p - q = 3

2 - q = 3

-q = 3 - 2 = 1

q = - 1

Therefore, p = 2 and q = -1

q = 2

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