Question

three consecutive terms of an arithametic sequence are 3,x and -5.what is x​

Answer 1

Answer:

X+3 3 X--1 7X--2 are 3 terms of Arithmateci Swquence (AP)

Common difference =3X-1 -X—3 =2X -4

2) 7X--2-3X+1 =4X--1

They are equal being common diffrence

4X-1=2X -4

2X = —3

X= — 3/2

First term =X+3 = --3/2+2 = (--3+4) /2 = -1/2

-1/2 -11/2 -25/2 ------2--b

Sum of n terms of AP = n/2 [ 2a +(n-1) d]

a= -- 1/2 d= -3/2

Sn= n/2 [ --1 +(n-1) (--3/2)]

Extension of the problem( For students of 10th to 12th )

Find sum of 10 terms

S10 = 10/2 [ --1 +9 (-3/2)]

=5 (-29/2)

=-- 145 /2 = — 72.5

S10 = --72.5

Step-by-step explanation:

plz mark brainlest