Answer 1

Here are some threads about recursion it may help you to know why we use this.
it somehow avoid as may be memory is out of bound in the case of right recursive function. compiler can handle left recursive function although. if left recursion is occurs in any function and it calls itself again and again then an deadlock situation is created so in case of left recursive function we need to eliminate the left recursion then we can use recursion so it will time and memory consuming so in case of left recursive function recursion is avoidable.
https://www.sololearn.com/discuss/1486703/?ref=app
https://www.sololearn.com/discuss/1386899/?ref=app
https://www.sololearn.com/discuss/120350/?ref=app
https://www.sololearn.com/discuss/271746/?ref=app
https://www.sololearn.com/discuss/1366/?ref=app
https://www.sololearn.com/discuss/1149517/?ref=app
https://www.sololearn.com/discuss/307407/?ref=app
https://www.sololearn.com/discuss/311837/?ref=app