Question

Assinale a alternativa que apresenta a forma reduzida do polinômio resultante da multiplicação (2× + 1) (7 _ ×).
a) -2×2 + 14 - × + 7
b) -2×2 + 13× + 7
c) 2×2 + 14×
d) 14× + 7

Answer 1

(2× + 1) (7 - ×)

2x.7 -2x.x +1.7 -1.x

14x -2x² +7 -x

-2x² +13x +7 ===> b)

Answer 2

$(2x+1)(7-x)=14x-2{x}^{2}+7-x$

$\boxed{\boxed{(2x+1)(17-x)=-2{x}^{2}+13x+7}}$

$\mathtt{alternativa }\\\mathtt{b}$