Question

Preciso de ajuda para resolver esses dois sistemas

Answer 1

$a)\\\\Use~o~metodo~da~adicao\\ \\ ~~~~~~~-x+~~~2y~~~~=15~.........~equacao~I\\~~+~~~~~ x+~~~~\frac{y}{7} ~~~~=~0~.........~equacao~II~(some~as~equacoes)\\ ~~~~~~--------\\ ~~~~~~~~~~0+(2y+\frac{y}{7}) =15\\ \\ 2y+\frac{y}{7} =15\\ \\mmc=7\\ \\ \frac{14y+y=105}{7} \\ \\ despreze~o~denominador\\ \\ 14y+y=105\\ \\ 15y=105\\ \\ y=\frac{105}{15} \\ \\ y=7\\ \\ substitua~(y=7)~em~uma~das~equacoes\\\\ -x+2y=15\\ \\ -x+2.7=15\\ \\ -x+14=15\\ \\ -x=15-14\\ \\ -x=1~.(-1)\\ \\ x=-1\\ \\ S=(x=-1;~~y=7)$

$b)~~metodo~da~substituicao\\ \\ 2x+y=5~........~equacao~I\\ \\ y=8x~........~equacao~II\\ \\ substitua~(y=8x)~na~equacao~I\\ \\ 2x+y=5\\ \\ 2x+8x=5\\ \\ 10x=5\\ \\ x=\frac{5}{10}\\\\ x=\frac{1}{2} \\ \\ substitua~(x=\frac{1}{2} )~na~equacao~II\\ \\ y=8x\\ \\ y=8.\frac{1}{2} \\ \\ y=\frac{8}{2} \\ \\ y=4\\ \\ S=(x=\frac{1}{2} ;~~y=4)$