Question

13 – Descubra o valor numérico de: 4x . (3x2 + 2x + 1) – 2 . (6x3 + 4x 2 + x) para x = 3/7.

Answer 1

Oie, Td Bom?!

>>> Resposta: O valor numérico é $\frac{6}{7}$ .

>>> Resolvendo a expressão.

$4x \: . \: (3x {}^{2} + 2x + 1) - 2(6x {}^{3} + 4x {}^{2} + x)$

>>> Substitua: $x = \frac{3}{7}$ .

$4 \: . \: \frac{3}{7} \: . \: (3 \: . \: ( \frac{3}{7} ) {}^{2} + 2 \: . \: \frac{3}{7} + 1) - 2(6 \: . \: ( \frac{3}{7} ) {}^{3} + 4 \: . \: ( \frac{3}{7} ) {}^{2} + \frac{3}{7} )$

$4 \: . \: \frac{3}{7} \: . \: (3 \: . \: \frac{9}{49} + \frac{6}{7} + 1) - 2(6 \: . \: \frac{3 {}^{3} }{7 {}^{3} } + 4 \: . \: \frac{9}{49} + \frac{3}{7} )$

$4 \: . \: \frac{3}{7} \: . \: ( \frac{27}{49} + \frac{6}{7} + 1) - 2(6 \: . \: \frac{27}{7 {}^{3} } + \frac{36}{49} + \frac{3}{7} )$

$4 \: . \: \frac{3}{7} \: . \: \frac{118}{49} - 2( \frac{162}{7 {}^{3} } + \frac{36}{49} + \frac{3}{7} )$

$\frac{1416}{343} - 2( \frac{162}{7 {}^{3} } + \frac{57}{49} )$

• Use a propriedade distributiva da multiplicação e multiplique cada termo dentro dos parênteses por $- 2$ .

$\frac{1416}{343} - \frac{324}{7 {}^{3} } - \frac{114}{49}$

$\frac{618}{343} - \frac{324}{7 {}^{3} }$

$\frac{618}{343} - \frac{324}{343}$

$\frac{618 - 324}{343}$

$\frac{294}{343} = \frac{294 \div 46}{343 \div 94} = \frac{6}{7}$

Att. Makaveli1996