Odpowiedź:
1.
A) 3x + 4 = 16
3x = 12 / : 3
x = 4
B) 6x - 5 = x + 4
6x - x = 4 + 5
5x = 9 /: 5
x = 1,8
C) 3(x + 5) = 2x - 4
3x + 15 = 2x - 4
3x - 2x = - 4 - 15
x = - 19
2.
[tex]x - \frac{5 \times + 1}{3} = \frac{1}{4} \times 3 = 3x - 5x + 1 = \frac{1}{4} \times 3 = - 2x = - 0.25 \div ( - 2) = x = 0.125[/tex]
3.
A)6 + x = (23 - x) - (17 - 2x)
6 + x = 23 - x - 17 + 2x
x + x - 2x = 23 - 17 - 6
0 = 0
B) 3x + x + (2 + x) = 3(x - 1)
3x + x + 2 + x = 3x - 3
2x = - 5 / : 2
x = - 2,5
C)2x + 5 = 8(1 + 0,25x)
2x + 5 = 8 + 2x
2x - 2x = 8 - 5
0 = 3
D)
[tex] \frac{x}{6} - \frac{x}{3} = 7 - \frac{x}{4} \times 6 = x - 2x = 21 - \frac{3x}{2} = x - 2x = 21 - \frac{3x}{2} \times 2 = 2x - 4x = 42 - 3x = x = 42[/tex]
4.
-2x(4x + 2) = 0
-8x2 + 4x = 0
