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Va rog frumos ajutați-ma , | x-1| + |2x -2 | +|3x-3|+ ......+ | 9 x - 9 | = 90


Răspuns :

|x-1|+|2(x-1)|+|3(x-1)|+....+|9(x-1)|=90
|x-1|+2|x-1|+...+9|x-1|=90
(1+2+...+9) |x-1|=90
(9*10/2 )*|x-1|=90
|x-1|/2=1
|x-1|=2
deexci
x-1=2....  x=3
x-1=-2......x=-1
S={-1;3}


am folosit |a*b|= |a| *|b| si daca a >0, |a|=a