Let WWW be the subspace of R4\mathbb{R}^4R4 defined by x1+x2−x3=0x_1 + x_2 - x_3 = 0x1+x2−x3=0 and x2+x3−x4=0x_2 + x_3 - x_4 = 0x2+x3−x4=0. Which vector is in WWW?
(1,1,2,3)(1, 1, 2, 3)(1,1,2,3)
(1,0,1,1)(1, 0, 1, 1)(1,0,1,1)
(1,2,3,4)(1, 2, 3, 4)(1,2,3,4)
(0,1,1,2)(0, 1, 1, 2)(0,1,1,2)