Question

If in an ap., a = 15, d=-3 and an =0.then find the value of b

Answer 1

probably the answer is 4

Answer 2

Answer :-

Given :-

First term (a) = 15

Common difference (d) = -3

Last term (an) = 0

To Find :-

Number of terms n

Solution :-

$\huge{\boxed{\boxed{an \:=\: a \: +\:(n - 1)d}}}$

Putting values

» 0 = 15 + (n - 1)-3

» -15 = -3n + 3

» -15 - 3 = -3n

» -18 = -3n

» -18/-3 = n

» 6 = n

$\huge{\boxed{\boxed{n \:=\:6}}}$