![\"\"](\"/images/stars/stars-13.gif\")
You can put this solution on YOUR website!
I have a graph with numbers 10,30,60,100,150,210,280,360 and so on. I am having trouble finding the correct fomular for this problem.
\n" ); document.write( "thank you for your help
\n" ); document.write( "WHAT DO YOU WANT?
\n" ); document.write( "FORMULA FOR N TH. TERM???ASSUMING SO ......NOTE THE FOLLOWING
\n" ); document.write( "A2-A1=30-10=20
\n" ); document.write( "A3-A2=60-30=30
\n" ); document.write( "A4-A3=100-60=40
\n" ); document.write( "A5-A4=150-100=50
\n" ); document.write( "A6-A5=210-150=60
\n" ); document.write( "A7-A6=280-210=70
\n" ); document.write( "A8-A7=360-280=80
\n" ); document.write( "..............
\n" ); document.write( "WE ARE HAVING A.P. ON RHS 20,30,40,50...ETC..WITH D=10...TN=20+(N-1)*10=10N+10=10(N+1)...HENCE...TN-1=10(N-1+1)=10N\r
\n" ); document.write( "\n" ); document.write( "AN-A(N-1)=10N.........CHECK ABOVE PUTTING N=2,3,4 ETC....
\n" ); document.write( "------------------------ADDING ALL
\n" ); document.write( "AN-A1=20+30+................10N
\n" ); document.write( "AN-10=(N-1)[20+10N]/2=5(N-1)(N+2)
\n" ); document.write( "AN=10+5(N-1)(N+2)
\n" ); document.write( "CHECK
\n" ); document.write( "N=1.......A1=10
\n" ); document.write( "N=2.......A2=10+5*4=30
\n" ); document.write( "N=3.......A3=10+5*2*5=60
\n" ); document.write( "N=4.......A4=10+5*3*6=100.....
\n" ); document.write( "......ETC....OK \n" ); document.write( "