x = -5x=−5 is parallel to y-axis. So, there is no meeting with y-axis to make an intercept. Being perpendicular to x-axis, its slope is tan 90^o = oo90o=∞.
Explanation:
Compare the equation x = -5x=−5 with the form x = y/m + ax=ym+a. 1/m = 0 ( m=oo )1m=0(m=∞) and the x-intercept a = -5−5..