Mistake with A^2 - B^2

In algebra, a very common mistake you can see learner making is the below:

5² - 2² = (5 - 2)² = 3² = 9

This is very interesting.

It seems to be correct. That is the problem with this form of mathematical operation.

If you are aware that A² - B² = (A + B)(A - B), then this mistake will not occur.

It is this slip-of-the-mind type of human error.
It occurs when you are not alert or too tired after too many assignment quesions.

The correct answer is 5² - 2² = 25 - 4 = 21.
Or (5 + 2)(5 - 2) = 7 x 3 = 21.
Simple?

This is why maths is interesting. It catches you when you are not alert!

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