Question

Помогите! дам 40 балов!
Срочно! Очень нужно

Answer 1

$1);5z^2-2z-3=0\D=4+4cdot5cdot3=64\z_{1,2}=frac{2pm8}{10}\x_1=-frac35,;x_2=1\\2);x^2+x-20=0\D=1+4cdot20=81\x_{1,2}=frac{-1pm9}2\x_1=-5,;x_2=4\\3);x^2+9x+18=0\D=81-4cdot18=9\x_{1,2}=frac{-9pm3}2\x_1=-6,;x_2=-3\\4);m^2+5m-50=0\D=25+4cdot50=225\m_{1,2}=frac{-5pm15}2\m_1=-10,;m_2=5\\5);10a^2+30a+20=0;;div10\a^2+3a+2=0\D=9-4cdot2=1\a_{1,2}=frac{-3pm1}2\a_1=-2,;a_2=-1$

$a);frac{3m^2-4m-4}{6-m-m^2}\3m^2-4m-4=0\D=16+4cdot3cdot4=64\m_1=-frac23,;m_2=4\m^2+m-6=0\D=1+4cdot6=25\m_1=-3;m_2=2\frac{3m^2-4m-4}{6-m-m^2}=frac{3(m+frac23)(m-2)}{(m+3)(m-2)}=frac{3m+2}{m+3}\\b);frac{25-x^2}{x^2-8x+15}\x^2-8x+15=0\D=64-4cdot15=4\x_{1,2}=frac{8pm2}2\x_2=3,;x_2=5\frac{25-x^2}{x^2-8x+15}=frac{(x-5)(x+5)}{(x-3)(x-5)}=frac{x+5}{x-3}$