1) 5x-2=13
5x=13+2
5x=15 |:5
x=3
2) 2x-5≤15
2x≤15+5
2x≤20 |:2
x≤10
3) x=?
a) x-314=712 => x=712+314 => x=1026
b) 236+x=304 => x=304-236 => x=68
4) x=?
a) 144:x=36 => x=144:36 => x=4
b) 27:x+5=14 => 27:x=14-5 => 27:x=9 => x=27:9 => x=3
5) 2(x+3)<307-251
2x+6<56
2x<56-6
2x<50 |:2
x<25
6) 2^x+1≤16
2^x+1≤2^4
x+1≤4
x≤4-1
x≤3
7) 2*{12+3*[60-3*(27-4*3)]}-5x=7
2*{12+3*[60-3*(27-12)]}-5x=7
2*[12+3*(60-3*15)]-5x=7
2*[12+3*(60-45)]-5x=7
2*(12+3*15)-5x=7
2*(12+45)-5x=7
2*57-5x=7
114-5x=7
-5x=7-114
-5x=-107 |:(-5)
x=21,4
8) a+a+1+a+2+a+3=90
4a+6=90
4a=90-6
4a=84 |:4
a=21
9) a=prima zi ; b=a doua zi ; c=a treia zi
b=a+3
c=b+3
a+b+c=18
a+a+3+b+3=18
a+a+3+a+3+3=18
3a+9=18
3a=18-9
3a=9 |:3
a=3 probleme
b=a+3=3+3=6 probleme
c=b+3=6+3=9 probleme
Sper ca te-am ajutat.. Coroana?
