Question 930687

{{{4x-5y=22}}}......eq.1

{{{x+2y=-1}}}.......eq.2...multiply by {{{-4}}}
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{{{4x-5y=22}}}......eq.1

{{{-4x-8y=4}}}.......eq.2
_________________________add eq.1 and eq.2

{{{4x-5y+(-4x-8y)=22+4}}}

{{{4x-5y-4x-8y=26}}}

{{{cross(4x)-5y-cross(4x)-8y=26}}}

{{{-5y-8y=26}}}...solve for {{{y}}}

{{{-13y=26}}}

{{{y=26/-13}}}

{{{highlight(y=-2)}}}

go to eq.2, substitute {{{-2}}} for {{{y}}}

{{{x+2(-2)=-1}}}.......eq.2

{{{x-4=-1}}}...solve for {{{x}}}

{{{x=4-1}}}

{{{highlight(x=3)}}}

solution is: ({{{3}}},{{{-2}}})



{{{ graph( 600, 600, -10, 10, -10, 10, 4x/5-22/5,-x/2-1/2) }}}