Question

(
$(a +b ) {}^{2} =( a + b) (a + b) = a {}^{2} ab + ab + b {}^{2} = a {}^{2} 2ab + b {}^{2}$
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Answer 1

Esto es incorrecto:

$a^2ab+ab+b^2$

$a^22ab+b^2$

Esto es correcto:

$(a+b)^2=a^2+2ab+b^2$