there seems to be a problem with derivative

Questions
,
1

NDSolve[{Derivative[1][x][t] == 0.5[x[t]][1 + x[t]][2 - x[t]] y[t],
Derivative[1][y][t] == -y[t]^2 - 1.5 x[t] y[t]^2, x[0] == 4,
y[0] == 10000}, {x, y}, {t, 1000}]
this is not getting solved as it says non numerical derivative found at t==0.
Can anyone help me in this regard?

2

You have used [ and ] instead of ( and ) and those have completely different meanings to Mathematica.

In[2]:= NDSolve[{x'[t] == 0.5 (x[t]) (1 + x[t]) (2 - x[t]) y[t], 
  y'[t] == -y[t]^2 - 1.5 x[t] y[t]^2, x[0] == 4, y[0] == 10000}, {x, y}, {t, 1000}]

Out[2]= {{x ->InterpolatingFunction[{{0.`,1000.`}},<>],
y -> InterpolatingFunction[{{0.`,1000.`}},<>]}}
3

See also:

syntax problem in code

(repeated posting)