Check the continuity
f(x) = (\begin{cases} 2x, if \; x < 0\ 0, \;if\; 0\leq x\leq 1\4x, \; if \;x > 1 \end{cases})
Case (i) : The domain of the function is R
f(1) = 0, LHL ≠ RHL hence discontinuous at x = 1
How ever the function is continuous
when a < 0, 0 < a < 1 and a > 1
Hence x = 1 is the only point of discontinuity.