Question

2,3 Subiectul I
2,3,4 Subiectul II
Urgent

Answer 1

Rezolvarea in atasamente

Answer 2

Sub. I
2.{0,1}, {0,2}, {1,2}. Raspuns : trei
3.9a²-4b²=12 <=>(3a-2b)(3a+2b)=12
Daca 3a-2b=2 =>3a+2b=12:2 =>3a+2b=6

Sub.II
2.a+b+c=53
a+1=b+3 =>a=b+2
c=13
b+2+b+13=53
2b=38
b=19
a=21
3.9a+27b=10a+25b =>a=2b
   21b+7c=10b+40c =>11b=33c =>b=3c =>c=b/3
(2b+b-b/3)/(6b-b+b/3)=(3b-b/3)/(5b+b/3)=8b/16b=8/16=1/2
4.(√7+2)⁻¹=1/(√7+2)=(√7-2)/3
   (√7-2)⁻¹=1/(√7-2)=(√7+2)/3
(√7-2)/3+(√7+2)/3=(√7-2+√7+2)/3=2√7/3
√7=2,64...
2,64·0,(6)=1,76...
5/3=1,(6)
=>1,76...∈(5/3, 2)