Explicație pas cu pas:
[tex]a) \: 10x = 40 \\ x = 40 \div 10 \\ x = 4 \\ proba = 10 \times 4 = 40 \\ \\ b) \: - 7x = 21 \\ x = 21 \div ( -7) \\ x = - 3 \\ proba = - 7 \times ( - 3) = 21 \\ \\ c) \: 16x = 48 \\ x = 48 \div 16 \\ x = 3 \\ proba = 16 \times 3 = 48 \\ \\ f) \: 3 = - 2x + 7 \\ 3 + 2x = 7 \\ 2x = 7 - 3 \\ 2x = 4 \\ x = 4 \div 2 \\ x = 2 \\ proba = 3 = - 2 \times 2 + 7 \\ 3 = - 4 + 7 \\ 3 = 3 \\ \\ e) \: - 3x + 15 = 0 \\ - 3x = 0 - 15 \\ - 3x = - 15 \\ x = - 15 \div ( - 3) \\ x = 5 \\ proba = - 3 \times 5 + 15 \\ = - 15 + 15 = 0 \\ \\ g) \: 22x + 44 = 0 \\ 22x = 0 - 44 \\ 22x = - 44 \\ x = - 44 \div 22 \\ x = - 2 \\ proba = 22 \times ( - 2) + 44 \\ = - 44 + 44 = 0 \\ \\ i) \: - 18 + 6x = 6 \\ 6x = 6 + 18 \\ 6x = 24 \\ x = 24 \div 6 \\ x = 4 \\ proba = - 18 + 6 \times 4 \\ = - 18 + 24 = 6 \\ \\ j) \: - x + 7 = 23 \\ - x = 23 - 7 \\ - x = 16 \\ x = - 16 \\ proba = -( - 16) + 7 \\ =16 + 7 \\ = 23 \\ \\ k) \: 4(x - 7) = 0 \\ 4x - 28 = 0 \\ 4x = 0 + 28 \\ 4x = 28 \\ x = 28 \div 4 \\ x = 7 \\ proba = 4 \times (7 - 7) \\ = 4 \times 0 = 0[/tex]
Succes!
