4. soru (10.00 puan) Which of the following is not a subspace of R² A) {(x₁, x₂) x₁ + x₂ = 0, x₁, x₂ ER} {(x₁, x₂) x₁ + x₂-1=0, x₁, x₂ ER} {(x₁, x₂) x₁ - 2x₂ = 0, x₁₁, x₂ ER} {(x₁, x₂) x₁ + 3x₂ = 0, x₁, x₂ ER} [(x₁, x₂): 2x₁ - x₂ = 0, x₁, x₂ ER} O B) D) OE)