1a ((1,5-3,5)(1.5+3.5))²=(-2x5)²=100
b (√18-√8)(√50-√32)=(3√2-2√2)(5√2-4√2)=√2x√2=2
2a (x²-6x+8)/(x²-2x)=(x-4)(x-2)/x(x-2)=(x-4)/x
b (a-4)/a=1-4/a
1∈Z
4/a∈Z⇔a divide 4, a∈{-1,-2,-4,1,2,4}
3b ABCD patrat, AB≡BC≡CD≡AD
ABEF romb AB≡BE≡EF≡AF
deci BC≡BE ΔBCE isoscel, , deci mas BEC=mas ECB=30
suma unghiurilor in Δ este 180, 30+30+m(EBC)=180, m(EBC)=120
