Saturday, June 2, 2012

Brain Teasers: Equation Gone Wrong

Hey all! Can anyone figure out what went wrong?

a = b
ab = b^2
ab - a^2 = b^2 - a^2
a(b - a) = (b - a)(b + a)
a = b + a
                                                          a = b;          a = a + a
a = 2a
1 = 2?

What happened?






Solution: Look at Steps 4 and 5 in my justification above:

a(b - a) = (b - a)(b + a)
a = b + a

If a = b, then b - a = 0, so the real justification would be:

a(0) = (0)(b + a)
0 = 0

This means I divided by 0 in my justification, which is impossible according to the laws of mathematics.

Hope you enjoyed!

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