Question

me ajudem por favor!​

Answer 1

Resposta:

a) $S=\{4\}$

b) $S=\{1\}$

c) $S=\{8\}$

d) $S=\{6\}$

e) $S=\{-21\}$

f) $S=\{9\}$

Explicação passo a passo:

Para encontrar a raiz de uma equação de primeiro grau, basta isolar a incógnita (no caso, $x$) em um dos membros (lados) da equação e a parte numérica em outro.

Item a:

$3x-4=8\\\\3x-4+4=8+4\\\\3x=12\\\\\frac{1}{3}\times 3x=\frac{1}{3}\cdot12\\\\x=4$

Portanto:

$S=\{4\}$

Item b:

$5+4x=9\\\\5-5+4x=9-5\\\\4x=4\\\\\frac{1}{4}\times4x=\frac{1}{4}\times4\\\\x=1$

Portanto:

$S=\{1\}$

Item c:

$2x-8=8\\\\2x-8+8=8+8\\\\2x=16\\\\\frac{1}{2}\times2x=\frac{1}{2}\times16\\\\x=8$

Portanto:

$S=\{8\}$

Item d:

$3x+1=19\\\\3x+1-1=19-1\\\\3x=18\\\\\frac{1}{3}\times3x=\frac{1}{3}\times18\\\\x=6$

Portanto:

$S=\{6\}$

Item e:

$\frac{x}{7}+5=2\\\\\frac{x}{7}+5-5=2-5\\\\\frac{x}{7}=-3\\\\7\times\frac{x}{7}=7\times(-3)\\\\x=-21$

Portanto:

$S=\{-21\}$

Item f:

$7+\frac{x}{3}=10\\\\7-7+\frac{x}{3}=10-7\\\\\frac{x}{3}=3\\\\3\times\frac{x}{3}=3\times3\\\\x=9$

Portanto:

$S=\{9\}$