Question

desenvolva e reduza (5×+2)2 + (5×-2)2 - (5×+2). (5×-2)
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Answer 1

    $(5x+2)^{2}+(5x-2)^{2}-(5x+2)*(5x-2)=$

$=((5x)^{2}+2*5x*2+2^{2})+((5x)^{2}-2*5x*2+2^{2})-((5x)^{2}-2^{2})=$

$=25x^{2}+20x+4+25x^{2}-20x+4-(25x^{2}-4)=$

$=25x^{2}+20x+4+25x^{2}-20x+4-25x^{2}+4=$

$=25x^{2}+25x^{2}-25x^{2}+20x-20x+4+4+4=$

$=25x^{2}+12$