persamaan linear 2x + 5y = 11 dan 3x - 4y = -18 bila x dan y di ketahui maka tentukan nilai dari 5x - 7y

<p><strong>1. Eliminasi</strong>, &nbsp;eliminasi x untuk mendapat nilai y</p><p>Buat nilai x menjadi 0</p><p>3×(2x+5y=11) ---&gt; 6x+15y=33</p><p>2×(3x–4y=–18)--&gt; <u>6x–8y= -36</u> –</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;15y–(-8y)= 33–( -36)</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;23y = 69</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;y = 69÷23</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;y = 3</p><p><strong>2. Substitusi </strong>nilai y=3 ke salah satu persamaan</p><p>2x+5y=11</p><p>2x+5(3)=11</p><p>2x+15= 11</p><p>2x &nbsp; &nbsp; &nbsp; = 11 –15</p><p>2x &nbsp; &nbsp; &nbsp; = -4</p><p>x &nbsp; &nbsp; &nbsp; &nbsp; = -2</p><p>&nbsp;</p><p><strong>x= -2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;y=3</strong></p><p>5x–7y=</p><p>5(-2) –7(3)=</p><p>-10–21= -31</p>