Question

помогите пж. даю 30 балов!!!!!!

Answer 1

$\displaystyle\bf\\(y-3)(y+3)+y(5-y)-16y=y^{2} -3^{2} +y\cdot 5+y\cdot(-y)-16y=\\\\=y^{2}-9+5y-y^{2}-16y=\underbrace{(y^{2} -y^{2} )} _{0}+\underbrace{(5y-16y)}_{-11y}-9=-11y-9\\\\\\y=-\frac{1}{2} \\\\\\-11y-9=-11\cdot\Big(-\frac{1}{2}\Big)-9=5,5-9=-3,5 \\\\\\Otvet \ : \ -3,5$