Question

Which of the following linear equations has an undefined slope when plotted?

• A. $x=3$
• B. $y=0$
• C. $x=-y$
• D. $x-y=0$

Answer 1

The correct option is A $x=3$

Lines which are perpendicular to $x$ axis have undefined slope.

Option A has undefined slope, Option B has $0$ slope, Option C has $-1\left(\tan \right(-{45}^0\left)\right)$ as its slope and Option D has unity $\tan \left({45}^0\right)$ as its slope.