if c-d = 9 and c+2d=3, what is the value of c squared plus d squared

Question

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Answer 1

If we subtract the second equation from the first equation, we obtain,

 

  c - d = 9

-(c + 2d) = 3

______________

       -3d = 6

 

          d = -2

 

 

Next, we substitute this value of d into the first equation and solve for c.

 

c - (-2) = 9

c + 2 = 9

 

c = 7

 

 

Using your known values of c and d.

 

c² + d² = ?