Question

помогите пожалуйста срочно только 3)​

Answer 1

$y=-\frac{3}{8}x+7,5 \\\\1)y=-1\\\\-1=-\frac{3}{8}x+7,5\\\\\frac{3}{8}x=1+7,5\\\\\frac{3}{8}x=8,5\\\\x=8,5:\frac{3}{8}=8,5*\frac{8}{3}=\frac{85}{10} *\frac{8}{3}=\frac{17}{2}*\frac{8}{3}=\frac{136}{6}=22\frac{2}{3}\\\\\boxed{x=22\frac{2}{3}}$

$2)y=1\\\\1=-\frac{3}{8} x+7,5\\\\\frac{3}{8} x=-1+7,5\\\\\frac{3}{8}x=6,5\\\\x=6,5:\frac{3}{8}=6,5*\frac{8}{3}=\frac{65}{10}*\frac{8}{3}=\frac{13}{2}*\frac{8}{3}=\frac{52}{3}=17\frac{1}{3}\\\\\boxed{x=17\frac{1}{3} }$

$3)y=-\frac{2}{3}\\\\-\frac{2}{3} =-\frac{3}{8} x+7,5\\\\\frac{3}{8} x=\frac{2}{3} +7,5\\\\\frac{3}{8} x=\frac{2}{3}+\frac{15}{2}\\\\\frac{3}{8}x=\frac{4+45}{6}\\\\\frac{3}{8}x=\frac{49}{6}\\\\x=\frac{49}{6} :\frac{3}{8}=\frac{49}{6}*\frac{8}{3}=\frac{49*4}{3*3}=\frac{196}{9}=21\frac{7}{9}\\\\\boxed{x=21\frac{7}{9}} \\\\\\4)y=5\\\\5=-\frac{3}{8} x+7,5\\\\\frac{3}{8} x=7,5-5\\\\\frac{3}{8}x=2,5$

$x=2,5:\frac{3}{8} =\frac{5}{2} *\frac{8}{3}=\frac{5*4}{3}=\frac{20}{3}=6\frac{2}{3} \\\\\boxed{x=6\frac{2}{3} }$