А - 4 будет т.к дроби нужно сократить одинаковые и умножить
-2х² - 5х + 6 = 0,
Д = (-5)² - 4*(-2)*6 = 25 + 48 = 73,
х1 = -(5 + √73)/4,
х2 = -(5 - √73)/4,
х1 + х2 = -2*(-(-5+√73)/4 - (5-√73)/4) = -2*(5-√73+5+√73)/4) = -2*(10/4) = -5,
или по теореме Виета:
х1 + х2 = -р = -5
1450руб----------100%
xруб---------20%
x=1450*20/100=290
1450руб-290руб =1160руб
Ответ: 1160 руб
Sin(73π/24)*sin(37π/24)*sin(37π/12)=sin(3π+π/24)sin(π+13π/24)sin(3π+π/12)=
-sinπ/24*(-sin13π/24)*(-sinπ/12)=-1/2(cos(13π/24-π/24)-cos(13π/24+π/24))*
*sinπ/12=-1/2(cosπ/2-cos7π/12)*sinπ/12=1/2cos7π/12*sinπ/12=
=1/4(sin(π/12-7π/12)+sin(π/12+7π/12))=1/4(sin(-π/2)+sin2π/3)=
=1/4*(-1)+1/4*√3/2=-1/4+√3/8