let V = R^{4}. Consider the following subspaces:
U = { (a,b,c,d) in R^{4} : a + 2b + 3c = 0, a + b + c + d = 0 }
W = { (a,b,c,d) in R^{4} : a + d = 0, b + c = 0 }
find a basis for U and a basis for W.
i don't even know where to begin. Any help would be very much appreciated. Thanks.