What's the importance of vector in neural networks

Question

Machine learning

Answer 1

I think we dont need them
https://code.sololearn.com/clqW42eJH17t/?ref=app
but it simplifies calculation, as you can use matrix multiplication, instead of using long loop....

Answer 2

Neural networks base on vectors and matrices

Answer 3

So why do we need vector in implementing (a+b)*2 formula in neural networks