Question

Resolva as equações do 1º grau e encontre o valor das incógnitas.
a) 5. (K - 4) + 4 = 2.( -2k - 2 )

b) 4r - 4 = 1 - 2r

c) 7.( x - 4 ) = 17

d) 9x - 4x + 10= 7x - 30

Answer 1

Resposta:

a) 5. (K - 4) + 4 = 2.( -2k - 2 )

$5k - 20 + 4 = - 4k - 4 \\ 5k - 16 + 4k + 4 = 0 \\ 9k - 12 = 0 \\ 9k = 12 \div (3) \\ 3k = 4 \\ \\ k = \frac{4}{3}$

b) 4r - 4 = 1 - 2r

$4r - 4 - 1 + 2r = 0 \\ 6r - 5 = 0 \\ 6r = 5 \\ \\ r = \frac{5}{6}$

c) 7.( x - 4 ) = 17

$7x - 28 = 17 \\ 7x - 28 - 17 = 0 \\ 7x - 45 = 0 \\ 7x = 45 \\ \\ x = \frac{45}{7}$

d) 9x - 4x + 10= 7x - 30

$5x + 10 = 7x - 30 \\ 5x + 10 - 7x + 30 = 0 \\ - 2x + 40 = 0 \\ - 2x = - 40 \times ( - 1) \\ 2x = 40 \div (2) \\ x = 20$