<s>[INST] Squared binomial paradox? When you square this $$(5-2)^2$$ you will get 49 $$ 5^2 - 2 * 5 * (-2) + (-2)^2$$
$$25 + 20 + 4 = 49$$ but if you do it like this (5-2) * (5-2) you will get 9 $$ 5(5-2) - 2(5-2)$$
$$25-10-10+4$$
$$25-20+4$$
$$5+4$$
$$9$$
Why do I always get different results if I'm doing the same thing?Am I doing something wrong?
 [/INST] The binomial formular is $(a + b)^2 = a^2 + 2ab + b^2$
If you apply it:
$$(5 - 2)^2 = 5^2 + 2\cdot5\cdot(-2) + 2^2 = 25-20 + 4 = 9$$
The second binomial formular is  $(a - b)^2 = a^2 - 2ab + b^2$
If you apply it:
$$(5 - 2)^2 = 5^2 - 2\cdot5\cdot 2 + 2^2 = 25-20 + 4 = 9$$
Your mistake was, that you used the second binomial formular but took $a$ as $-2$ instead as $2$. 
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