Rozwiąż układ równań dla 2x=8 i y=x+7

Rozwiązanie zadanego układu równań metodą podstawiania:

$\begin{cases}2x=8 \\ y=x+7 \end{cases}$

$0?+2x=8?-x=7 $
$ $
$ $
$varc=document.getElementById("myCanvas"); $
$varctx=c.getContext("2d"); $
$ctx.font="18pxArial"; $
$ctx.strokeStyle="#202020";ctx.strokeStyle="#b22222";ctx.strokeText("?",7,24);ctx.font="12pxArial"; $
$ctx.moveTo(27,24);ctx.lineTo(291,24);ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("15",7,48);ctx.moveTo(27,48);ctx.lineTo(291,48);ctx.stroke(); $
$ctx.strokeText("14",7,72);ctx.moveTo(27,72);ctx.lineTo(291,72);ctx.stroke(); $
$ctx.strokeText("13",7,96);ctx.moveTo(27,96);ctx.lineTo(291,96);ctx.stroke(); $
$ctx.strokeText("12",7,120);ctx.moveTo(27,120);ctx.lineTo(291,120);ctx.stroke(); $
$ctx.strokeText("11",7,144);ctx.moveTo(27,144);ctx.lineTo(291,144);ctx.stroke(); $
$ctx.strokeText("10",7,168);ctx.moveTo(27,168);ctx.lineTo(291,168);ctx.stroke(); $
$ctx.strokeText("9",7,192);ctx.moveTo(27,192);ctx.lineTo(291,192);ctx.stroke(); $
$ctx.strokeText("8",7,216);ctx.moveTo(27,216);ctx.lineTo(291,216);ctx.stroke(); $
$ctx.strokeText("7",7,240);ctx.moveTo(27,240);ctx.lineTo(291,240);ctx.stroke(); $
$ctx.strokeText("6",7,264);ctx.moveTo(27,264);ctx.lineTo(291,264);ctx.stroke(); $
$ctx.strokeText("5",7,288);ctx.moveTo(27,288);ctx.lineTo(291,288);ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("-2",19,310);ctx.moveTo(27,0);ctx.lineTo(27,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("-1",43,310);ctx.moveTo(51,0);ctx.lineTo(51,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("0",67,310);ctx.moveTo(75,0);ctx.lineTo(75,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("1",91,310);ctx.moveTo(99,0);ctx.lineTo(99,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("2",115,310);ctx.moveTo(123,0);ctx.lineTo(123,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("3",139,310);ctx.moveTo(147,0);ctx.lineTo(147,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("4",163,310);ctx.moveTo(171,0);ctx.lineTo(171,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("5",187,310);ctx.moveTo(195,0);ctx.lineTo(195,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("6",211,310);ctx.moveTo(219,0);ctx.lineTo(219,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeText("7",235,310);ctx.moveTo(243,0);ctx.lineTo(243,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.strokeStyle="#202020";ctx.strokeStyle="#b22222";ctx.font="18pxArial"; $
$ctx.strokeText("x",259,310);ctx.font="11pxArial"; $
$ctx.moveTo(267,0);ctx.lineTo(267,290);ctx.strokeStyle='#eee9e9';ctx.stroke(); $
$ctx.beginPath();ctx.moveTo(169,0);ctx.lineTo(169,288);ctx.lineWidth=3;ctx.strokeStyle="#ff3399";ctx.stroke(); $
$ctx.beginPath();ctx.moveTo(289,24);ctx.lineTo(27,288);ctx.lineWidth=3;ctx.strokeStyle="#006633";ctx.stroke(); $

i: Ostateczne rozwiązanie to:

  2x = 8 

  x = 4 
  -(4) + y = 7
  y = 11
  y = 11 
  x = 4
  y = 11 {x,y} = {4,11}