2. a² + b2 = c2

a=9 b=40

I don't know if you meant b^2 and c^2 or b x 2 and c x 2 so I'll do both.

If it's meant to be multiplied by 2, then you do 9^2 + (40) 2 = c2

81 + 80 = c2

161 = c2

/2

80.5 = c

However I do doubt it's that. This means it's likely meant to be squared instead. In which case, use the following answer.

9^2 + 40^2 = c^2

1681 = c^2

Then square root both sides to get just c (which i assume is what you're trying to find?)

Square root of 1681 = 41

So your answer would be 41.