Question

Encontra ao valor da incognita e das equaçoes
b-7_2 +8=0
3m-5_2 = m-3_5
3x_5 + 1_2 = 3_4
2.(x-1)_3 = 5

Answer 1

Olá!

Questão a)

$\dfrac{b-7}{2} +8=0\\ \\ \\ \dfrac{b-7}{2} =-8\\ \\ \\ b-7=-8\times~2\\ \\ b-7=-16\\ \\ b=-16+7\\ \\\\ \boxed{b=-9}$

Questão b)

$\dfrac{3m-5}{2} =\dfrac{m-3}{5} \\ \\ \\ 5\times(3m-5)=2\times(m-3)\\ \\ 15m-25=2m-6\\ \\ 15m-2m=-6+25\\ \\ 13m=19\\ \\\\ \boxed{m=\dfrac{19}{13} }$

Questão c)

$\dfrac{3x}{5} +\dfrac{1}{2}=\dfrac{3}{4} \\ \\ \\ \dfrac{3x}{5} =\dfrac{3}{4}-\dfrac{1}{2}\\ \\ \\ \dfrac{3x}{5} =\dfrac{3-2}{4} \\ \\ \\ \dfrac{3x}{5} =\dfrac{1}{4} \\ \\ \\4\times3x=5\times1\\ \\ 12x=5\\ \\ \\ \boxed{x=\dfrac{5}{12} }$

Questão d)

$\dfrac{2\times(x-1)}{3} =5\\ \\ \\ 2\times(x-1)=5\times3\\ \\ 2x-2=15\\ \\ 2x=15+2\\ \\ 2x=17\\ \\\\ \boxed{x=\dfrac{17}{2} }$

:)