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(2x+1)²-(x-7)(x+7)-3x(x+4)

Răspuns :

(2x+1)(2x+1)=4x la 2+4x+1
(x-7)(x+7)=x la 2-49
3x(x+4)=3x la 2 +12x

4x la 2+4x+1-x la 2+49-3x la 2-12x=8x+50

=4x²+4x+1-x²+7²-3x²-12x=-8x+50