Question

find S5 of the AP 8 6 4​

Answer 1

Answer:   s5 =20

Step-by-step explanation:   AP 8,6,4

a=8      d= 6-8 = - 2

s5= n/2{2a+(n-1)d}

= 5/2{16+(5-1)(-2)}

= 5/2{8}

= 5*4

= 20

hope it will help

Answer 2

Given,

AP = 8, 6, 4

a = 8

To Find,

S5 =?

Solution,

Common difference(d) = $a_2 -a_1$

d = 6 - 8 = - 2

From formula of sum up to n terms in AP,

$S_n = n/2[2a + (n -1) * d]$

$S_5= 5/2[2 * 8+ (5-1) * (-2)]$

$S_5= 5/2[16 + 4 * (-2)]\\S_5= 5/2[16 - 8]\\S_5= 5* 8 / 2 = 40 / 2\\S_5 = 20$

Hence, S5 of the AP 8, 6,  4,​ is  20.