Let B = (~u1, . . . , ~un) be an orthonormal basis of Rn, and let ~x be a vector in Rn. Like any vector in Rn, ~x can be expressed as a linear combination of ~u1, . . . , ~un, say ~x = c1~u1 + + cn~un. Simplify ~x ~uk, expressing your answers in terms of c1, . . . , cn. (b) Let ~u1 = 1 7 2 3 6 , ~u2 = 1 7