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1. Verificati daca x = -1 este solutie a inecuatiei :
a ) 3 - x√2 > 5.
b ) x + 2x - 1/5 ≥ -1 .
c ) 3(2x-3) < 2(x-4) -5.


Răspuns :

a)-x√2>5-3
-x√2>2 =>x√2<2 =>x<2√2/2 =>x<√2

b)3x-1/5≥-1
3x≥1/5-1
3x≥-4/5 =>x≥-4/15

c)6x-9<3x-8-5
6x-3x<9-8-5
2x<-4 =>x<-2
a) 3-(-1√2) > 5
3+ √2 > 5
(√1 < √2 < √4 => √2=1,..)
3+ 1,..>5 Fals

b) -1 + 2(-1) - 2/10 >= -1
-1 -2- 0,2 >= -1
-3,2>= -1 Fals

c) 3(2•-1-3) <2(-1-4)-5
3(-2-3) <2(-5) -5
3(-3) < -10-5
-9<-15 Fals