42х=1008
х=1008:42
х=24
ответ: 24
x²-2x-224
D= 4+896=900
x1= (2+30)/2= 16
x2= (2-30)/2= -14
(x-16)*(x+14)
или
x²-2x-224= x²-16x+14x-224= x(x-16)+14(x-16)= (x+14)*(x-16)
B^2-16=(b-4)(b+4)
a^2+6a+9=(a+3)^2
Один корень => дискриминант = 0
![3x^2+px-p=0 \\ D=p^2+12p=0 \\ p(p+12)=0 \\ p_1=0 \\ p_2=-12](https://tex.z-dn.net/?f=3x%5E2%2Bpx-p%3D0+%5C%5C+D%3Dp%5E2%2B12p%3D0+%5C%5C+p%28p%2B12%29%3D0+%5C%5C+p_1%3D0+%5C%5C+p_2%3D-12)
tg(3*π/2 - α) * sin(2*π - α) = (- ctg α) * (- sin α) = cos α / sin α * sin α = cos α