10. a) | a-b|=0, ⇒ a-b=0 ⇒ a=b
|5a-4b+54|=0 , daca a=b
|5a-4a+54|=0, a+54=0, a=b=-54
b) |a+b|=0, a= - b
2a+3b+5=0, -2b+3b+5=0, b+5=0, b=-5, a=5
c) 3a-9=0, 3a=9, a=3
7a-b+1=0, 21-b+1=0, 22-b=0, b=22
13, a) ||x-4|-4|=8
|x-4|-4=8, |x-4|=12,
I. x-4=12, x=12+4,x=16 sau
II. x-4=-12, x=-8
e) |4x-1|=15,
4x-1=15, 4x=16, x=4
4x-1=-15, 4x= - 14, x=-14/4=-7/2= - 3,5
14. Trebuie sa vedem care sunt modulele . Pt aceasta trebuie sa compar
3√3 cu 5, Ridic la patrat si obtin 9*3 si 25, 27>25 ⇒ 3√3>5
|3√3-5|=3√3-5
Compar 4 cu 2√5, 16 cu 4*5, 16<20 ⇒4<2√5
|4-2√5|=2√5-4
√3<√5, |√3-√5|=√5-√3
n=2(3√3-5)-3(2√5-4)+6(√5-√3)=6√3-10-6√5+12+6√5-6√3=2
