SOLUTION: hi please help me thank you very much. Which of the following is an intermediate step if the given equations are to be solved by elimingating one unknown by addition? {{{system(

Algebra ->  Equations -> SOLUTION: hi please help me thank you very much. Which of the following is an intermediate step if the given equations are to be solved by elimingating one unknown by addition? {{{system(      Log On


   

Question 160327: hi please help me thank you very much. Which of the following is an intermediate step if the given equations are to be solved by elimingating one unknown by addition?
system%28+5x+%2B+5Y+=+1%2C++3x+-+8y+=+5%29
the anwsers are
A)system%2840x+%2B+40y+=8%2C++15x+-+40y+=+25%29
B)system%2815x+%2B+15y+=+3%2C++15x+-+40y+=25%29
C)system%285x+%2B+5y+=+1%2C+++y+=+%283x+-+5%29%2F8%29
D)system%28x+=+%281+-+5y%29%2F5%2C+x+=%285+%2B+8y%29%2F3%29
Found 2 solutions by checkley77, Edwin McCravy:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
Answer is A).
40x+40y=8
15x-40y=25 adding these 2 equations eliminates the y terms.
---------------------
55x=33

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Edwin's solution:
hi please help me thank you very much. Which of the following is an intermediate step if the given equations are to be solved by elimingating one unknown by addition?
system%28+5x+%2B+5Y+=+1%2C++3x+-+8y+=+5%29
the answers are
A)system%2840x+%2B+40y+=8%2C++15x+-+40y+=+25%29
B)system%2815x+%2B+15y+=+3%2C++15x+-+40y+=25%29
C)system%285x+%2B+5y+=+1%2C+++y+=+%283x+-+5%29%2F8%29
D)system%28x+=+%281+-+5y%29%2F5%2C+x+=%285+%2B+8y%29%2F3%29 

The correct answer is A) because
when added vertically, the terms matrix%281%2C2%2C%22%2B%22%2C40y%29 and -40y
will cancel out like this:

A)system%2840x+%2B+cross%2840y%29+=8%2C++15x+-+cross%2840y%29+=+25%29

and the sum adding vertically will be the equation:

   55x =  33   

which is easily solved for x.

Edwin