How do solve the following linear system?: # -9x+5y=1 , -x+5y=-13 #?

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Answer 1 · 2015-11-26T12:15:44

#x=-7/4#, #y=-59/20#

From the second equation, you have that #x=5y+13#. Substitute this expression for #x# in the first equation to have

#-9(5y+13)+5y=1#. Expand:

#-45y-117+5y=1#. Isolate the #y# terms:

#-40y = 118#. Solve for #y#:

#y=-118/40 = -59/20#.

Once #y# is known, we can find back #x#:

#x=5y+13 = 5*(-59/20)+13 = -7/4#.