Question

2) (1 - y) + 8y = 7 + y(3 - y);

Answer 1

Ответ:

Объяснение:

(1 - y) + 8y = 7 + y(3 - y)

1 - y + 8y = 7 + 3y - y²

1 - y + 8y - 7 - 3y + y² = 0

$[begin{gathered}{y^2}+4y-6=0hfill\D={b^2}-4ac={4^2}-4cdot 1cdot (-6)=16+24=40hfill\{y_{1;2}}=frac{{-bpmsqrt D}}{{2a}}=frac{{-4pmsqrt {40}}}{{2cdot1}}=frac{{-4pm2sqrt {10}}}{2}=frac{{2(-2pmsqrt {10})}}{2}=-2pmsqrt {10}hfill\{y_1}=-2+sqrt {10}hfill\{y_2}=-2-sqrt {10}hfill\end{gathered}]$