a=√7-√2
b=√7+√2
a)
1/a+1/b=1/(√7-√3)+1/(√7+√2) rationalizam si obtinem
(√7+√2)/(√7-√3)(√7+√2) + (√7-√2)/(√7-√3)(√7+√2)=
(√7+√2+√7-√2)/(√7²-√2²)=(2√7)/(7-2)=2√7/5
√7≈2,64 iar 2*2,64≈5,28 ⇒1/a+1/b apartine intervalului
b)media artimetica
(a+b)/2=(√7-√2+√7+√2)/2=2√7/2=√7
c)(a-b)²=(√7-√2+√7+√2)²=(2√7)²=4*7=28
