The 3rd term of an A.P is 4x – 2y and the 9th term is 10x – 8y. Find the common difference.
- 19x - 17y
- 8x - 4y
-
x - y
- 2x
The correct answer is: C
Explanation
n = 3, U\(_3\) = 4x - 2y,
U\(_n\) = a + (n-1)d,
4x - 2y = a + 2d... (1)
U\(_9\) = 10x - 8y,
10x - 8y = a + 8d... (2)
Solving (1) and (2),
subtract eqn i from ii
a-a + 8d - 2d = 10x -4x - 8y- (-2y)
6d = 6x - 8y+ 2y.
6d= 6x - 6y
6d = 6( x-y)
d = x - y
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