5.A. 3C= A− BB. 8 7 .C= B− AA. 8 7 .5 105 10M= ± D. 5C= − B+ AM= ±

5

.

A.

3

c

=

a

b

B.

8

7

.

c

=

b

a

A.

8

7

.

5

10

m

= ±

D.

5

c

= −

b

+

a

m

= ±