Question: Why does the proof for 1=2 not work?
x = 1
Draw a picture showing y = x and y= x2.
On the picture, you will see TWO things:
So the "=" in line three is an "=" of points, not of functions or graphs. You do not take the derivative of a point - but of a graph.
It would now be your choice as to WHICH of lines 3 or 4 you wanted to say had the flaw in logic.
The way to test the logic in such a string of equations is to substitute, in each line, and SEE when the statements SWITCH from true to false. Good logic always takes a true statement to a true statement. Anything that takes a true statement to a false statement is bad logic!
Line 3 is written as if you can substitute any value of x. However, it is only true if x= 0 or 1.Walter