(√4+X)+(√4-x)=8
ridicam la puterea a doua ambele parti ale egalitatii
(√4+x)²+(√4-x)²=64
aplicam formula (a+b)²=a²+2ab+b² si (a-b)²=a²-2ab+b²
4+2x√4+x²+4-2x√4+x²=64
8+2x²=64
2x²=56
x²=28
x=√28
