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rezolvati in multimea numerelor intregi
a. (-3 la putere 2)X(x-1)+(-3)la putere 2 = 7X (2x +3) + 20
b. 9X(x+2) < 5x + 20


Răspuns :

(-3)²X(x-1)+(-3)² = 7X (2x +3) + 20
9X(x-1)+9 = 14x+21 + 20
9x-9+9=14x+41
14x-9x=-41
5x=-41
x=-41:5
x=-8,2

b) 9X(x+2)<5x+20
9x+18<5x+20
9x-5x<20-18
4x<2
x<2/4
x<1/2
x<0,5