To find the x-intercept, set y to 0.

a) This one has no x-intercept, y is always -5 so it never crosses the x axis (which is defined by y=0).

b) 0=-3x+9

3x=9

x=3

So the x intercept is (3,0) or just 3.

c) 2x+3(0)-6=0

2x-6=0

2x=6

x=3

Same answer as b).

d) x is always equal to -4 regardless of y, so the x intercept is (-4,0).

Hope that helps.