Question 253660
<pre><font size = 4 color = "indigo"><b>
Learn the Cramer's rule setup:

{{{system(Ax + By = C,
          Dx + Ey = F)}}}

{{{x = (abs(matrix(2,2,C,B,F,E)))/(abs(matrix(2,2,A,B,D,E)))=("CE-BF")/("AE-BD")}}}

{{{y = (abs(matrix(2,2,A,C,D,F)))/(abs(matrix(2,2,A,B,D,E)))=("AF-CD")/("AE-BD")}}}

{{{system(x-2y=1,2x+y=7)}}}

Put in the understood 1 coefficients

{{{system(1x-2y=1,2x+1y=7)}}}

A=1, B=-2, C=1, D=2, E=1, F=7

{{{x = (abs(matrix(2,2,1,-2,7,1)))/(abs(matrix(2,2,1,-2,2,1)))=((1)(1)-(-2)(7))/((1)(1)-(-2)(2))=(1+14)/(1+4)=15/5=3}}}

{{{y = (abs(matrix(2,2,1,1,2,7)))/(abs(matrix(2,2,1,-2,2,1)))=((1)(7)-(1)(2))/((1)(1)-(-2)(2))=(7-2)/(1+4)=5/5=1}}}

Edwin</pre>