Mathematics

Problem

Consider the function $f(x)=\begin{cases} px+1,& x<3, 4x+q,& x\ge 3. \end{cases}$ Which one of the following conditions on

p

and

q

is necessary and sufficient for

f

to be continuous at

x=3

? a)

p+1=12+q

3p=12+q

3p+1=12+q

3p+1=4p+q