My laptop is only using 1 memory slot

Hi i have a HP ProBook 4740s  and according to my task manager, I'm only using 1 memory slot(I have 2), is this mandatory and can i use both for better performance

Its not the best Computer but i just need to know if i can use both

My CPU specs just in-case
Please send help
I did not know what to input so i put Inspiron, pls redirect me to a person who can add help me just incase