For this case we have to apply the following transformation:
(x, y) -------> (4x, 4y) --------> (x ', y')
Applying the transformation to the vertices we have:
(-2, 1) -------> (4 (-2), 4 (1)) --------> (-8, 4)
(-1, -1) -------> (4 (-1), 4 (-1)) --------> (-4, -4)
(-2, -2) -------> (4 (-2), 4 (-2)) --------> (-8, -8)
Answer:
Stretching △DEF horizontally and vertically by a factor of 4 results in the transformed points
D '(-8, 4)
E '(-4, -4)
F '(-8, -8)