Explicație pas cu pas:
2)
a) -x = 7 - 21 <=> -x = -14 => x = 14 (da)
b) 3x - 35 = 1 <=> 3x = 1 + 35 <=> 3x = 36 => x = 12 (nu)
c) x : 2 = 9 <=> x = 2×9 => x = 18 (da)
d) -16 : x = -2 <=> -16 = -2x => x = 8 (nu)
3)
a)
[tex] - 4x - 36 = 0 \\ - 4x = 36 = > x = - 9[/tex]
b)
[tex] - 4x + 1 = - 15 \\ - 4x = - 16 = > x = 4[/tex]
c)
[tex] - 6x + 4 = - 8 \\ - 6x = - 12 = > x = 2[/tex]
d)
[tex]5x + 17 = 2 \\ 5x = - 15 = > x = - 3[/tex]
e)
[tex] - 3x + 4 = - 5 \\ - 3x = - 9 = > x = 3[/tex]
f)
[tex]5x - 3 = 3x + 11 \\ 5x - 3x = 11 + 3 \\ 2x = 14 = > x = 7 \\ [/tex]
g)
[tex]4x + 13 = 3x + 15 \\ 4x - 3x = 15 - 13 = > x = 2[/tex]
h)
[tex]5(x - 1) = 2x + 7 < = > 5x - 5 = 2x + 7 \\ 5x - 2x = 7 + 5 < = > 3x = 12 \\ = > x = 4[/tex]
i)
[tex]3(2x - 5) = 6(x - 1) - 9 \\ 6x - 15 = 6x - 6 - 9 \\ 6x - 6x = - 15 + 15 \\ 0x = 0 = > x\in \mathbb{Z}[/tex]
j)
[tex]6(5 - 3x) = 20 - 5(4 + 3x) \\ 30 - 18x = 20 - 20 - 15x \\ - 18x + 15x = - 30 \\ - 3x = - 30 = > x = 10[/tex]
k)
[tex]7(3x - 4) + 19 = 3(5x - 7) \\ 21x - 28 + 19 = 15x - 21 \\ 21x - 15x = - 21 + 9 \\ 6x = - 12 = > x = - 2[/tex]
l)
[tex]((x + 3) - 4) - 8 + x = 11 \\ (x + 3 - 4) + x = 11 + 8 \\ x - 1 + x = 19 < = > 2x = 19 + 1 \\ 2x = 20 = > x = 10[/tex]
m)
[tex] - 3(2x - 5) + 7x - 9 = - 5x - 2(9 - 3x) + 24 \\ - 6x + 15 + 7x - 9 = - 5x - 18 + 6x + 24 \\ x + 6 = x + 6 < = > 0x = 0 = > x\in \mathbb{Z}[/tex]
3)
a)
[tex]4x + 16 = 12 < = > 4x = 12 - 16 \\ 4x = - 4 = > x = - 1 \not \in \mathbb{N}[/tex]
b)
[tex]5x + 6 = 31 < = > 5x = 31 - 6 \\ 5x = 25 = > x = 5[/tex]
c)
[tex]4(x - 3) + 9 = 5 < = > 4x - 12 + 9 = 5 \\ 4x - 3 = 5 < = > 4x = 8 \\ = > x = 2[/tex]
d)
[tex](((2x - 6) \div 5) \div 4) \div 2 = 3 \\ ((2x - 6) \div 5) \div 4 = 6 \\ (2x - 6) \div 5 = 24 \\ 2x - 6 = 120 < = > 2x = 126 \\ = > x = 63[/tex]