if(x+2),(x+50and(2x*3+1)are 3 consective term of an A.P.fine the posible value of x
then assuming by x*3 you mean x^3,
2x^3 + 1 - (x+50) = x+50 - (x+2)
2x^3 - x - 49 = 48
2x^3 - x - 97 = 0
this has no simple solution, so I ran it trough the
Wolfram equation solver, and got
x = 3.69252
http://www.wolframalpha.com/input/?i=2x%5E3+-+x+-+97+%3D+0+
so the numbers are
x+2 = 5.69252
x+50 = 53.69252 and
2x^3+1 = 101.69283
check: 101.69283-53.69252 = 48.003
53.69252-5.69252 = 48
looks ok