Design black box test suit for :-(software engineering question)

i)a function that checks whether a character string(of upto twenty five characters in length) is a palindrome

ii)a function that takes the name of the book as input and searches a file containing the names of the books available in the Library and displays the details of the book if the book is available in the library otherwise displays the message "book not available"

iii)a program that accepts upto ten simultaneous linear equations in up to ten independent variables and displays the solution