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fisa de lucru ecuatii si inecuatii pentru clasa a7-a
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Ecuatii si inecuatii in multimea numerelor naturale
Ecuatii. La ecuatiile prezentate ca aplicatii la operatiile de adunare, scadere si inmultire mai adaugam pe cele referitoare la impartirea si ridicare la putere. Exemple: 1. X:7=11 are Solutia x=7 . 11, adica x=77.
2. 480:x = 24 are Solutia x=480 : 24 adica x=20. 3. x5 = 35 => x = 3.
4. 2x+1 = 32 / 2x + 1 => x+5 = 1 adica x=4. Inecuatii. In toate tipurile de ecuatii de mai sus inlocuind semnul ,,=’’ cu unul dintre semnele < sau >, < sau > se obtin inecuatii in numere naturale.
1. Rezolvati ecuatiile:a) x + 8 = 17 b) 13 + x = 24 c) x – 5 =13 d) 18 – x = 3
________________________________________________________________________________________________________________________________________________________________________ e) x + 3 = 78 f) 71 + x = 108 g) x – 23 = 15 h)102 – x = 15________________________________________________________________________________________________________________________________________________________________________2. Determinati numarul x: a) 12 . x = 144 b) x . 4 = 156 c) x: 6 = 1751 d) x: 19 = 57________________________________________________________________________________________________________________________________________________________________________
3. Rezolvati, in multimea numerelor naturale, ecuatiile:a) 7x = 73 b) 52x + 1 = 513 c) 252x + 1 = 518 d) 43x+1 = 210
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4. Precizati pentru care dintre ecuatiile de mai jos este o solutie numarul natural 10:a) x + 23 = 33 b) 2x – 5 = 25 c) 4x + 11 = 51d) 7x + 4 = 6x + 12 e) 9x + 7 . 6 = 3x – 18 f) 133x = 1330
5. Rezolvati, in multimea numerelor naturale, inecuatiile:a) x + 3 < 4 b) x : 4 < 5 c) 7x + 12 > 19 d) 13x – 2 > 132001
e) x + 5 > 17 f) 4x < 35 g) 112x + 1 < 117