Question

como resolvo
1) Resolva as equações:
a) 2(2x + 1) = 30
b) –(3x + 4) = (3 – 5x)
c) 8(10−k)=2k
d) 2x – 3(4 – x) = 5 + 4(2x + 1)
e) 2(x – 3) + 4(2x + 1) = 8 – 5(x – 4)
f) +(4x – 5) = -3(x – 4)

Answer 1

Resposta:

$2(2x + 1) = 30 \\ 2x + 1 = \frac{30}{2} \\ 2x + 1 = 12 \\ 2x = 15 - 1 \\ 2x = 14 \\ x = \frac{14}{2} \\ x = 7$

$b) - (3x + 4) = (3 - 5x) \\ - 3x - 4 = 3 - 5x \\ - 3x - 4 + 5x = 3 \\ 2x - 4 = 3 \\ 2x = 3 + 4 \\ 2x = 7 \\ x = \frac{7}{2}$

$c)8(10 - k) = 2k \\ 80 - 8k = 2k \\ 80 - 8k - 2k = 0 \\ 80 - 10k = 0 \\ - 10k = - 80 \\ k = \frac{ - 80}{ - 10} \\ k = 8$

$d)2x - 3(4 - \times ) = 5 + 4(2x + 1) \\ 2x - 12 + 3x = 5 + 4(2x - 1) \\ 5x - 12 = 5 + 4(2x - 1) \\ 5x - 12 = 5 + 8x - 4 \\ 5x - 12 = 1 + 8x \\ 5x - 12 - 8x = 1 \\ - 3x - 12 = 1 \\ - 3x = 1 + 12 \\ - 3x = 13 \\ x = \frac{13}{ - 3} \\ x = - \frac{13}{3}$

$e)2(x - 3) + 4(2x + ) = 8 - 5(x - 4) \\2x - 6 + 4(2x - 1) = 8 - 5(x - 4) \\ 2x - 6 + 8x + 4 = 8 - 5(x - 4) \\ 10x - 6 + 4 = 8 - 5(x - 4) \\ 10x - 2 = 8 - 5x + 20 \\ 10x - 2 = 28 - 5x \\ 10x - 2 + 5 = 28 \\ 15x - 2 = 28 \\ 15x = 28 + 2 \\ 15x = 30 \\ x = \frac{30}{15} \\ x = 2$

$f)+ (4x - 5) = - 3(x - 4) \\ 4x - 5 = - 3 \times + 12 \\ 4x - 5 + 3x = 12 \\ 7x = - 5 = 12 \\ 7x = 12 + 5 \\ 7x = 17 \\ x = \frac{17}{7}$

Answer 2

Por que 12 na letra A?

Explicação passo a passo: