(3/4x^2-1,4xy-2,5y+4)-(2y^2-7/5xy+0,75x^2) =
0,75x^2-1,4xy+2,5y+4-2y^2+1,4xy-0,75x^2=
2,5y-2y^2
У=кх+в
М(2;3) 3=2к+b
N(11;-5) -5=11k+b
Решаем систему!
{2k+b=3; {b=3-2k { b=3+16/9; {b=43/9
{11k+b=-5; {11k+3-2k=-5; 9k=-8; {k=-8/9 {k=-8/9
y=-8/9 x+43/9
-8x-9y=-43
<span>(cos 75-sin 75)²=cos²75-2sin75cos75+sin²75=1-sin2*75=1-sin150=1-sin(180-30)=1-sin30=1-0.5=0.5</span>