1.1 Given that the sum of two of its roots is zero, solve the equation: 6x-3x3+8x2-x+2 = 0. 1.2 From the following subgroups of GL2(C), pick out those which are abelian: a. the subgroup of invertible upper triangular matrices; b. the subgroup S defined by S == {[ a b -ba c. the subgroup U defined by 1.3 Let U = S3 {[ = a b ba ; a, b R, and a+b 16/2 6/ = 1}. :] ; a,b C, and [a] + |b| = 1}. {(21, 23, 24) (x1, x2, 3, 4) R4 4=1}. This can be identified with the set U of Question 1.2c above via the identi- fication a = xix2, b = x3 + 1x4 and hence automatically acquires a group structure. Compute the inverse of the element (, ) in this group. 2 2 2