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17. Show that u, v, and w are all in the span(u, v, w) 18. Determine if the given vectors are linearly independent 19. If vectors u, v, and w are linearly independent, will u +v, v +w. u+ w also be linearly independent? 20. Let 4 -2 1 -10 2 A= B= (a) Multiply A and B (b) Use the matrix column representation of the product to write each col- umn of AB as a linear combination of the columns of A. (c) Use the matrix row representation of the product to write each row of AB as a linear combination of the rows of B (d) Compute the outer product expansion of AB 21. Show that if the columns of B are linearly dependent, then so are the columns of AB