Lew Hodgett wrote:
Have fun.

Answer to follow.

Lew
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Let: a = b,
Then: (1) a^2 = ab,
(2) a^2 - b^2 = ab - b^2,
(3) (a + b)(a - b) = b(a - b),
(4) a + b = b,
(5) 2b = b,
(6) 2 = 1

It would seem that we have proved 2 = 1.

What is wrong here?

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From:

Basic Mathematics For Engineering And Science, Page 18, 1952

By:

Walter R Van Voorhis, PhD, Professor of Mathematics
Fenn College, Cleveland, Ohio

and

Elmer E Haskins, PhD, Professor of Mechanical Engineering
Fenn College, Cleveland, Ohio
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Illegal to divide by 0 in going from (3) to (4).

How about: Show that the square root of 2 is not a rational number (the
ratio of 2 integers)?