Question Number 114710 by mohammad17 last updated on 20/Sep/20

Answered by 1549442205PVT last updated on 20/Sep/20

We need find δ>0 such that∀x,y :  ∣x−0∣<δ,∣y−0∣<δ(1) then  ∣x^2 +y^2 −0∣<8 (2).Because  It is clear when ∣x∣<1 and ∣y∣<1  then ∣x^2 +y^2 ∣=2<8 hence,choosing δ=1  then for ∀x,y satisfy (1) the inequality  (2)is alway true.Therefore, in the  available answers  we choose a  (the other options don′t satisfy)