If the 4th term of an A.P is twice the 8th term, prove that the 10th term is twice the 11th term.

2 answers

4th term --- a + 3d
8th term ---- a + 7d

a+3d = 2(a+7d)
a+3d = 2a + 14d
-a = 11d
a = -11d

11th term = a + 10d
= -11d + 10d
= -d

10th term = a + 9d
= -11d + 9d
= -2d = twice -d = twice 11th term
It's a wrong solution