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K<br />

C<br />

A<br />

T<br />

PART B<br />

7. Simplify each of the following linear combinations and write your answer in<br />

component form:<br />

and<br />

a. 212a ! 3b ! a !<br />

c ! i ! 2j !<br />

2 41a ! , b ! <br />

b ! j ! <br />

c ! 3k ! ,<br />

2 1a ! c ! <br />

c ! i ! 3j ! 2k !<br />

2<br />

1<br />

b.<br />

2 12a! 4b ! 8c ! 2 1 3 13a! 6b ! 9c ! 2<br />

8. Name two sets of vectors that could be used to span the xy-plane in R 3 . Show<br />

how the vectors 11, 2, 02 and 13, 4, 02 could each be written as a linear<br />

combination of the vectors you have chosen.<br />

9. a. The set of vectors 511, 0, 02, 10, 1, 026 spans a set in R 3 . Describe this set.<br />

b. Write the vector 12, 4, 02 as a linear combination of these vectors.<br />

c. Explain why it is not possible to write 13, 5, 82 as a linear combination of<br />

these vectors.<br />

d. If the vector 11, 1, 02 were added to this set, what would these three<br />

vectors span in R 3 ?<br />

10. Solve for a, b, and c in the following equation:<br />

21a, 3, c2 31c, 7, c2 15, b c, 152<br />

11. Write the vector 110, 342 as a linear combination of the vectors 11, 32 and<br />

11, 52.<br />

12. In Example 3, it was shown how to find a formula for the coefficients a and b<br />

whenever we are given a general vector 1x, y2.<br />

a. Repeat this procedure for 512, 12, 11, 126.<br />

b. Write each of the following vectors as a linear combination of the set given<br />

in part a.: 12, 32, 1124, 52, and 14, 112.<br />

13. a. Show that the vectors 11, 2, 32, 14, 1, 22, and 114, 1, 162 do not lie<br />

on the same plane.<br />

b. Show that the vectors 11, 3, 42, 10, 1, 12, and 13, 14, 72 lie on the same<br />

plane, and show how one of the vectors can be written as a linear<br />

combination of the other two.<br />

14. Determine the value for x such that the points A11, 3, 42, B12, 3, 12, and<br />

C15, 6, x2 all lie on a plane that contains the origin.<br />

15. The vectors a ! and b !<br />

span What values of m and n will make the following<br />

statement true: 1m 22a ! R 2 .<br />

1n 32b ! ? Explain your reasoning.<br />

PART C<br />

16. The vectors 14, 1, 72, 11, 1, 62, and 1 p, q, 52 are coplanar. Determine three sets<br />

of values for p and q for which this is true.<br />

17. The vectors a ! and span For what values of m is it true that<br />

1m 2 2m 32a ! b !<br />

R 2 .<br />

1m 2 m 62b ! 0 ! ? Explain your reasoning.<br />

CHAPTER 6 341

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