1) | 1/2 -1/3 | + | 1/4 -1/3| aducem la acelasi numitor inauntrul modulelor
| 3/6 -2/6| + | 3/12 -4/12|=
= | 1/6 | + | -1/12|=
= 1/6 + 1/12= (2+1)/12= 3/12= 1/4
2) a² +b² -2a√3 + 6b√2 +21=0
a² -2a√3 + √3 +b² +6b√2 + 3√2=0
(a-√3)² +(b+3√2)²=0
|a-√3| =0 ∧ |b+3√2|=0
a-√3=0 b+3√2=0
a= √3 b= -3√2
