Problem #10: Simple Algebra

Given x = 1 and y = 1, we have

	x = y

Multiplying each side by x

	x² = xy

Subtracting y² from each side

	x² - y² = xy - y²

Factoring each side

	(x + y)(x - y) = y (x - y)

Dividing out the common term ((x - y) we have

	x + y = y

Substituting the given values

	1 + 1 = 1

	    2 = 1

What is wrong with this proof?

[Top | Solution]