Question

1. $\left \{ {{3x+y=7} \atop {-3x+4y=-2}} \right.$
2. $\left \{ {{x+y=-1} \atop {-2x-2y=2}} \right.$

3. 5x-7≥-4x+11
4. (X-2) •5+4≤(3x+2) 3-4
5. $\frac{29-2x}{3}$+7< $\frac{3x-11}{4}$-x
6. $\frac{12x+7}{3}$>3x+$\frac{1-x}{4}$

Answer 1

1.
 3x+y=7
-3x+4y=-2
_________
   /   5y=5 =>y=1 ; x=2

2.
   x+y=-1  |·2
-2x-2y=2
________
  /     /     /  => sistem cu solutii nedeterminate

3.
5x+4x≥7+11
9x≥18 =>x≥2 =>x∈[2, +∞)

4.
5x-10+4≤9x+6-4
5x-9x≤6+6-4
-4x≤8 sau 4x≥-8 =>x≥-2 =>x∈[-2, +∞)

5.
4(29-2x)+84<3(3x-11)-12x
116-8x+84<9x-33-12x
-8x+3x<-200-33
-5x<-233 sau 5x>233 =>x>233/5, asta daca dupa linia de fractie este -x...

6.
4(12x+7)>36x+3(1-x)
48x+28>36x+3-3x
48x-33x>-28+3
15x>-25 =>x>-25/15 sau x>-5/3 =>x∈(-5/3, +∞)