show that the points (-3,5), (3,1), (0,3) and (-1,-4) do not form a quadrilateral

 the points (-3,5), (3,1), and (0,3) form a line and would only allow a three-sided shape.
the equation of the line is y= -(2/3)x+3

hey vivek!

Cud u give a perfect answer, as this is a 4 marks question.

In return i assure u, a thumbs up.

 A quadrilateral is simply a figure with 4 sides (and some area inside the lines, unless you accept degenerate figures -- figures with area = 0).

Four distinct points will always form a quadrilateral...

UNLESS three of the points are on the same line. Then you get a triangle.

Look for a series of three points that follow the same slope:

y = mx + c

Step one, look for a common slope:

m = (diff. in y) / (diff in x)
remember that each point is given in the order (x, y) 

For example, going from point 1 to point 2
from (-3,5) to (3,1):

m = (5-1)/(-3 - 3) = 4/6

Check all the possible pairs. Look for pairs with the same m.

If you find combinations with the same m, then check the intercept (the value "c" in the line equation above). If both "m" and "c" are the same, then the line is the same.

Thanks, I got it.