Find three mutually orthogonal unit vectors in Bold Upper R cubed besides plus or minusi, plus or minusj, and plus or minusk. There are multiple ways to do this and an infinite number of answers. For this problem, we choose a first vector u randomly, choose all but one component of a second vector v randomly, and choose the first component of a third vector w randomly. The other components x, y, and z are chosen so that u, v, and w are mutually orthogonal. Then unit vectors are found based on u, v, and w. Start with uequalsleft angle1,0,3right angle, vequalsleft anglex, minus1,2right angle, and wequalsleft angle1,y, zright angle. The unit vector based on u is left angle nothing comma nothing comma nothing right angle.(Type exact answers, using radicals as needed.)

Suppose we have a set of small wooden blocks showing the 26 letters of the english alphabet, one letter per block. (think of scrabble tiles.) our set includes 10 copies of each letter. we place them into a bag and draw out one block at a time. (a) if we line up the letters on a rack as we draw them, how different ways coukl we fill a rack of 5 letters? (b) now suppose we just toss our chosen blocks into a pile, and whenever we draw a letter we already have, we put it back in the bag and draw again. how many different piles of 5 blocks could result? possible? piles will contain at least one repeated letter? (c) if we draw out 5 blocks wit hout looking at them, how many different piles are (d) if we draw out 5 blocks without looking at them, how many of the possible 2. (4) consider the following formula. 12 give two different proofs, one using the factorial formulas and the other combina torial.