Subtract

a2-b2 from a2 +b2
​

2b^2

Step-by-step explanation:

according to the question equation is

(a^2 + b^2 ) - (a^2 - b^2)

a^2 + b^2 - a^2 + b^2

plus a square and minus a square gets cancel

b^2 + b^2

since they are like terms they can be added

2b^2

one that is bigger than 3 1/2

tube or goog would be a great resource to with that question