Why is the middle term 2ab in (a+b) ^2 and - 2ab in (a-b) ^2 when written in standard form

Step-by-step explanation:

You can try to expand, then you will get the middle term as 2ab or - 2ab:

(a+b) ² = (a+b) (a+b)

= a² + ab + ab + b²

= a² + 2ab + b²

As for the (a-b) ², it will come in the same way:

(a-b) ² = (a-b) (a-b)

= a² - ab - ab + b²

= a² - 2ab + b²

(Hope you can understand)