Question 189479
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Given{{{system(2x+2y=16(red(EQN1)),2x+6y=28(red(EQN2)))}}}


In {{{red(EQN1)}}} we get,
{{{2y=-2x+16}}}--->{{{cross(2)y/cross(2)=(-2x+16)/2=(-2/2)x+16/2}}}
{{{y=-x+8}}}{{{red(EQN3)}}}, subst. in {{{red(EQN2)}}}:


{{{2x+6(red(-x+8))=28}}}
{{{2x-6x+48=28}}}----> {{{-4x=28-48=-20}}}--->{{{cross(-4)x/cross(-4)=cross(-20)5/cross(-4)}}}
{{{red(x=5)}}}, subst. in {{{red(EQN3)}}}:


{{{y=-red(5)+8=red(3)}}}


Then, these two lines intersect at point <font color=red>(5,3)</font>


We'll see,
{{{drawing(400,400,-4,15,-4,12,graph(400,400,-4,15,-4,12,-x+8,(28-2x)/6),blue(circle(5,3,.10)))}}} ---><font color=red>RED=EQN1</font>; <font color=green>GREEN=EQN2</font>


Thank you,
Jojo</font>