i added a file with the questions and the solutions of the book http://img178.imageshack.us/my.php?image=img7565zj6.jpg question 1 is: calculate "e" with an error less than 10^-9?? i started the solving of this problem by finding the expretion of Rn for e^X NEXT we need to chhose a point C which is located between X and A A<c<X i know that X equals to 1 but why in the solution they tell that A=0??? question 2 is: find cos 9 with an error less than 10^-5 (9 is degrees not radians) here after findinf the expretion of Rn where did i use to put "c" because they solve this problem without c i dont know why?? question 3: i dint understand the way they solved it because they didnt use any tailor series here where is the function that i need to build a tailor series from??