Well the general form for a vertical shear is

1 0

m 1

but you can also tell by multiplying it by the basis vectors.

[[1,0],[0,5]]*[1,0]=[1,0]

so you see the (1,0) vector does not change in the transformation, which should not be the case in a vertical shear. What this actually does is stretch everything out, because as you can see any y value is multiplied by 5, where in a shear transformation the magnitude of the y value changes according to the x value.