Question

the third term of an AP is 4. what is the sum of first five numbers​

Answer 1

Answer:

428&376

Step-by-step explanation:

37'byrj527-63

Answer 2

Answer:

a3= a+(n-1)d = 4

= a+2d=4   ------------(i)

=> a=4-2d

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

S5=$\frac{5}{2}[2(4-2d)+(5-1)d] \\= \frac{5}{2} [8-4d+4d]\\= \frac{5}{2} *8\\=5*4\\=20$