Question

hello. mate
plz solve this question step by step​

Answer 1

Step-by-step explanation:

$a = \frac{n}{2} (2a + (n - 1)d \\ 192 = \frac{8}{2} (2 \times 3 + 8 - 1 \times d) \\ 192 = 4 (6 + 7d) \\ \frac{192}{4} = 6 +7 d \\ 48 - 6 = 7d \\ \frac{42}{7 } = d \\ d = 6$

Answer 2

ix) Given a=3 , n=8 , S=192

find d.

so.

Sn=192

n/2(2a+(n-1)d=192

8/2{(2×3+(8-1)d}=192. (n=8)

4{6+7d}=192

6+7d = 192/4

6+7d=48

7d=48-6

d=42/7

Thus , d=6(Answer)

x) Given l=28 , S=144, n=9,a=?

so,

l=28

Now, Sn=144

S9=144

9/2(a+l)=144

a+l=144×2/9

a+28=16×2

a=32-28=4

Thus ,a=4(Answer)