Question 675181


{{{ x=-3y+4}}} ...........1...substitute in 2
{{{3x+9y=12}}}.............2
______________________________


{{{3(-3y+4)+9y=12}}}.............2...solve for {{{y}}}

{{{-9y+12+9y=12}}}


{{{-9y+9y=12-12}}}

{{{0=0}}}..............there are an {{{infinite}}} number of solutions and the system is {{{dependent}}}

so, the two lines are {{{identical}}} (one lies perfectly {{{on}}}{{{ top}}}{{{ of}}}{{{ the}}}{{{ other}}}) and intersect at {{{all}}} {{{points}}} of both lines