||'''Book'''|| Advanced Engineering Mathematics ||
 ||'''Author'''|| Erwin Kreyszig ||
 ||'''Edition'''|| 8th Edition ||

/* code_begins */

{{{
abs(4*a), 4*abs(a), abs(a - b)}}}

/* code_ends */

 * '''Solution by''': 
  * ganesh, developer, space
  * bhanukiran, student, technical university of Delft
  * saransh, student, sobhit university
  * ujwala, lecturer, aurangabad