3. (20%) Consider the space R and let: d(x, y) = la+ yl, ifsty 10, if a = y for all x, y e R. (a) Is it true that for every x, y e R, d(x, y) = d(y, )? (b) Does d, as described in Eq. (1), satisfy the triangle inequality? (c) Is d, as described above in Eq. (1), a metric