Question

решите систему уравнений 7х-5у=–2
х+у=1 3/35

Answer 1

$left { {{7x-5y=-2} atop {x+y= frac{13}{35} }} right. \ \ left { {{7x-5y=-2} atop {x= frac{13}{35}-y }} right. \ \ 7*( frac{13}{35}-y)-5y=-2 \ frac{13}{5}-7y-5y=-2 \ -12y=-2- frac{13}{5} \ -12y=- frac{23}{5} \ \ y= frac{23}{5}: frac{12}{1}= frac{23}{5}* frac{1}{12}= frac{23}{60} \ \ x+ frac{23}{60}= frac{13}{35} \ \ x= frac{13}{35}- frac{23}{60}= frac{780-805}{2100} = frac{25}{2100}= frac{1}{84}$