Any irrational number produces an irrational number when added to 3/4.
This is because 3/4 is rational (it can be represented as a ratio of two integers). You can get an irrational number only when you add rational to irrational (because rational to rational produces a rational sum).
if you look at delta y over x, you'll notice it always equals 2
i.e (22-2)/10-0 = 20/10 = 2
or (14-2)/6-0 = 12/6 = 2
or even (22-8)/10-3 = 14/7 = 2
This means that m (slope) is 2.
Now as for b. b is the y intercept and that value occurs when x = 0. On the table, when x = 0 y = 2 so b = 2.
y = mx + b becomes
y = 2x + 2
(a-b) X (a+b)
= aXa - bXa +aXb -bXb (distributing)
Now, cross product of a vector with itself = 0
so, aXa = 0, bXb = 0
Also, aXb = - bXa
so,
(a-b) X (a+b) = 0 + aXb + aXb + 0
= 2aXb
hence, proved :)