Question

which term of series 9-3+1-1/3+.........is-1/243

Answer 1

instead of___ we can put X
9-3+1-1/3+X=-1/243
7-1/3+X=-1/243
X=-1/243+7-1/3
X=-1/243+7/1-1/3
X=-1/243+20/3
(do cross multiple)(then you will get)
X=-4863/729


that is:9-3+1-1/3+-4863/726/9=-1/243