Math, asked by phoenix55, 10 months ago

if 1+4+7+10..........x=287 ,find the value of x

Answers

Answered by HARISHKABILAN

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

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

574 = n(2+3n-3)

3n^2 - n -574

n = 14

Sn = n/2(a+l)

287 = 14/2(1+x)

287/7 = x+1

41 -1 = x

so x = 40

phoenix55: x=40 is the right answer

HARISHKABILAN: now i did it correctly

phoenix55: where it is

HARISHKABILAN: what??¿¿

phoenix55: i need correct answer

HARISHKABILAN: i posted only the correct answer

HARISHKABILAN: if u have an doubt on it u cs search it on any where

phoenix55: kk

phoenix55: thanks

HARISHKABILAN: okkkkkk......

Answered by ssiva9557312

Answer:

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