Question

Find the fourth term from the end in an AP. -11,-8,-5,......49.
The answer is 40
Please show with proper steps...

Answer 1

-11,-8,-5,49

d=-8-(-11)
d=-8+11
d=3

ON REVERSING THE AP
a=49
d= -3

$an = a + (n - 1)d \\ \\ an = 49 + (4 - 1) \times - 3 \\ \\ an = 49 + 3 \times - 3 \\ \\ an = 49 - 9 \\ \\ an = 40$
So the fourth term from the end of this AP is 40