Question

for an A.P., find s8 if a=7
and d=5​

Answer 1

Answer:

196

Step-by-step explanation:

$\huge\boxed{ \mathfrak{\colorbox{gray}{Given :-}}}$

$\: \: \: \: : \implies \: first \: term \: ,a= 7$

$\: \: \: \: : \implies \: common \: difference ,d= 5$

$\color{yellow}\huge\boxed{ \mathfrak{\colorbox{blue}{To \: find:-}}}$

$\: \: \: \: : \implies \: sum \: of \: 8 \: terms,S8$

$\mathfrak{We \: know \: that, }$

$Sn = \frac{n}{2} (2a + (n - 1)d)$

$S8 = \frac{8}{2} (2 \times 7+ (8 - 1)5)$

$S8 = \frac{8}{2} (49)$

$\boxed{S8 = 196}$