Question

In the system -12c+3d=6 and -3c+6d=-9, which expression could you use for substitution?. A. d=-1/2c-3/2. B.c=-2d+3. C.c=1/4d-1/2. D. d=4c-2

Answer 1

The system:
- 12 c + 3 d = 6
- 3 c + 6 d = - 9
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The 1st equation:
- 12 c = - 3 d + 6 / * ( - 1) ( multiple both sides by -1 )
12 c = 3 d - 6 / : 12 ( divide both sides by 12 )
c = d / 4 - 1/2
Answer:
C ) c = 1/4 d - 1/2