Jambmaths question:
The 3rd term of an A.P is 4x – 2y and the 9th is 10x – 8y. Find the common difference.
Option A:
19x – 17y
Option B:
8x – 4y
Option C:
x – y
Option D:
2x
Jamb Maths Solution:
$\begin{align} & {{T}_{3}}=4x-2y---(i) \\ & {{T}_{9}}=10x-8y---(ii) \\ & {{T}_{3}}=a+2d----(iii)\text{ }\text{ }\!\!\{\!\!\text{ }{{T}_{n}}=a+(n-1)d\} \\ & {{T}_{9}}=a+8d----(iv) \\ & {{T}_{9}}-{{T}_{3}}=(10x-8y)-(4x-2y)=6x-6y---(v) \\ & {{T}_{9}}-{{T}_{3}}=6d------(vi) \\ & \text{Equating }(v)\text{ and }(vi) \\ & 6d=6x-6y \\ & d=x-y \\\end{align}$
Jamb Maths Topic:
Year of Exam: