Adding a string to a list adds each character separately

function = input('Enter function')
a = input('do you want to enter another function')
b = [function]
if a.lower() == 'yes':
    while True:
        function1 = input('Next Function')
        b += function1
        if function1 == 'quit':
            break

print(b)

in this code if I input in function1: y = 9x + 1; it will put the values in the array, but in the format: 'y', ' ', '9x', ' ', '+', ' ', '1'. how do save the input as y = 9x + 1'? Also when I write quit, it prints the array, but the final value is q','u','i','t'. How do I eliminate those values?

For your first request you can simply use .append() on b to append the element to the list b.

Code solving first issue:

b.append(function1)

For your second request you could simply check if quit was typed before appending element to b

Code solving second issue:

while True:
    function1 = input('Next Function: ')
    if function1 == 'quit':
        break
    b.append(function1)

Final Code:

function = input('Enter function: ')
a = input('Do you want to enter another function: ')
b = [function]
if a.lower() == 'yes':
    while True:
        function1 = input('Next Function: ')
        if function1 == 'quit':
            break
        b.append(function1)


print(b)