Question

please solve this. .​

Answer 1

Answer:

1+4+7+10+.....+x=287

x=287-22

x=265

Answer 2

Answer:

40

Step-by-step explanation:

here 1st term is 1 and common difference is 3,let number of terms be n then

now sum of all terms is n/2(1+x)=287----(1)

nd,x=1+(n-1)3

=>x=3n-2

now replacing x in eqn 1,in terms of x we got

n/2(1+3n-2)=287

=>n(3n-1)=287×2

=>3n^2-n-574=0

=>3n^2-42n+41n-574=0

=>3n(n-14)+41(n-14)=0

clearly n-14=0

=>n=14

so now x=3n-2=40