The given function is,
f( x )={ | x |+3 , x≤−3 −2x , −3<x<3 6x+2 , x≥3
Consider k be any real number, then the cases will be k<−3, k=−3, −3<k<3, k>3 or k=3.
When k<−3, the function becomes,
f( k )=−k+3
The limit of the function is,
lim x→k f( x )= lim x→k ( −x+3 ) =−k+3
It can be observed that, lim x→k f( x )=f( k ).
Therefore, the function is continuous for all real numbers less than −3.
When k=−3, the left hand limit of the function is,
LHL= lim x→ 3 − f( x ) = lim x→ 3 − ( −x+3 ) =−( −3 )+3 =6
The right hand limit of the function at k=−3 is,
RHL= lim x→ 3 + f( x ) = lim x→ 3 + ( −2x ) =( −2 )( −3 ) =6
It can be observed that, LHL=RHL.
Therefore, the function is continuous at x=−3.
When −3<k<3, the function becomes,
f( k )=−2k
The limit of the function is,
lim x→k f( x )= lim x→k ( −2x ) =−2k
It can be observed that, lim x→k f( x )=f( k ).
Therefore, the function is continuous in −3<k<3.
When k=3, the left hand limit of the function is,
LHL= lim x→ 3 − f( x ) = lim x→ 3 − ( −2x ) =−6
The right hand side of the function at k=3 is,
RHL= lim x→ 3 + ( 6x+2 ) =6( 3 )+2 =20
It can be observed that, LHL≠RHL.
Therefore, the function is discontinuous at x=3.
When k>3, the function becomes,
f( k )=6k+2
The limit of the function is,
lim x→k f( x )= lim x→k ( 6x+2 ) =6k+2
It can be observed that lim x→k f( x )=f( k ).
Therefore, the function is continuous for all numbers greater than 3.