Distributing a Power
It seems as though everyone wants (a+b)^2=a^2+b^2, and who wouldn’t? Every math exercise in the world becomes much easier if you use this! Unfortunately, in general, (a+b)^2
eq a^2+b^2. Its true in a trivial case – when a or b equals zero (plug zero in for either one to check). Otherwise, this is a no go and if you aren’t sure, try it out with some nonzero numbers: What if a=1 and b=1?
(1+1)^2=2^2=4 while 1^2+1^2=1+1=2. Clearly we get two different things. Now this isn’t a mathematical proof since I used two specific numbers but the fact that it does not work here should give you pause. In fact, you would have to FOIL the left hand side to find its equivalent expression. In other words, (a+b)^2=(a+b)(a+b)^2=a^2+2ab+b^2.