Question

a= +5,d= 3,n=4,find s4
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Answer 1

Answer:S4=38

Step-by-step explanation:

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

S4= 4/2(2.5 + (4-1)3)

S4= 2(10 + 3.3)

S4= 2(10+9)

S4= 2(19)

S4= 38

Answer 2

AnswEr :

$\:\bullet\:\sf\ a = +5$

$\:\bullet\:\sf\ d = 3$

$\:\bullet\:\sf\ n = 4$

$\:\bullet\:\sf\ S_4 = ?$

$\underline{\dag\:\textsf{According \: to \: given \: in \: question:}}$

$\normalsize\ : \implies{\boxed{\sf{S_n = \frac{n}{2}[2a + (n-1)d] }}}$

$\scriptsize\sf{\: \: \: \: \: \:( \therefore\ \: \red{Block \: the \: known \: values}) }$

$\normalsize\ : \implies\sf\ S_4 = \frac{4}{2}[2 \times\ 5 + (4 - 1)3] \\ \\ \normalsize\ : \implies\sf\ S_4 = \frac{\cancel{4}}{\cancel{2}}[10 + 9] \\ \\ \normalsize\ : \implies\sf\ S_4 = 2[19] \\ \\ \normalsize\ : \implies\sf\ S_4 = 38$

$\normalsize\ : \implies{\underline{\boxed{\sf \green{S_4 = 38}}}}$