A. 3x(x - 2) = 2x(x - 1)
3x² - 6x = 2x² - 2x
3x² - 2x² - 6x + 2x = 0
x² - 4x = 0
x(x - 4) = 0
x = 0 v x - 4 = 0
x = 4
B. 4x + 8 = 2x - 4
4x - 2x = -4 - 8
2x = -12|: 2
x = -6
C. 4(x - 2) = 3x + 4
4x - 8 = 3x + 4
4x - 3x = 4 + 8
x = 12
D. -(5 - x) + 13 = -x
-5 + x + 13 = -x
x + x = 5 - 13
2x = -8|: 2
x = -4
Odp: Liczba 4 spełnia równanie A. 3x(x - 2) = 2x(x - 1).