Question

Question

Answer 1

?

Answer 2

In Arithmetic Progression

\(\large \color{black}{\begin{align}

S_{15}=150, \ S_{25}=200 ,\ S_{n}=0,\ n=?\hspace{.33em}\\~\\


\end{align}}\)

Answer 3

God its been a while since I have done this I would be no help to you sorry

Answer 4

so you know the sum of Arithmetic series formula ?

Answer 5

\(n/2\left(2a+(n-1)d\right)\)

Answer 6

so with the given data,
can we form 2 equations in 2 unknowns and solve for 'a' and 'd'
?

Answer 7

yes

Answer 8

150 = 15 (a+ 7d)
200 = 25 (a+ 12d)

right ?

Answer 9

yes

Answer 10

so what values did u get for a and d ?

Answer 11

\(a=64/5,d=-2/5\)

Answer 12

for Sn = 0

2a+(n-1)d = 0
[because n can't be 0]

Answer 13

oh yes

Answer 14

so n is?

Answer 15

:)

Answer 16

\(\Huge \checkmark \)