Question

Помогите решить систему
{ х+c=10
х*(x+c) =30

Answer 1

Ответ:

$\left \{ {{x=10-c} \atop {x*(x+c)=30}} \right. \\(10-c)=(10-c+c)=30\\c=7\\x=10-7\\x=3\\(x,c)=(3,7)$

Объяснение:

Answer 2

$\displaystyle \tt \left \{ {{x+c=10} \atop {x(x+c)=30}} \right. \to \left \{ {{x=10-c} \atop {x(x+c)=30}} \right. \\\\\displaystyle \tt (10-c)(10-c+c)=30\\\displaystyle \tt (10-c)\cdot10=30\\\displaystyle \tt 100-10c=30\\\displaystyle \tt -10c=30-100\\\displaystyle \tt -10c=-70\\\displaystyle \tt c=\frac{-70}{-10}\\\displaystyle \tt \underline{\bold{c=7}}$

$\displaystyle \tt x=10-c=10-7=\bold{3}$

Ответ: $\displaystyle \tt (c;\:x)=(7;\:3)$