<span>16m^2-100n^2-16m^2+8mn-n^2=8mn-101n^2</span> можно n вынести за скобку....n(8m-101n)
<span>1,2x - 0,5x^2 = 4x^2 - 0,8x
2x - 4,5x^2 = 0
45x^2 - 20x = 0
9x^2 - 4x = 0
x(9x - 4) = 0
x =0
or
x = 4/9
0,6x^2 + V3x = 0
x(0,6x + V3) = 0
x =0
or
x = -5V3/3(V- корень)
9x^2 - 10x = 7x^2 - 15x
2x^2 + 5x = 0
x(2x + 5) = 0
x = 0
x = -2,5
2/3x^2 = 5x
2x^2 - 15x = 0
x(2x - 15) = 0
x = 0
x = 7,5</span>
Sinx+2cosx+sin3x=0
(sinx+sin3x)+2cosx=0
применим формулу суммы синусов
2sin(2x)*cosx+2cosx=0
вынесем cosx за скобки:
![cosx(sin(2x)+1)=0 \\cosx=0 \\x_1=\frac{\pi}{2}+\pi n,\ n \in Z \\sin(2x)=-1 \\2x=-\frac{\pi}{2}+2\pi n,\ n \in Z \\x_2=-\frac{\pi}{4}+\pi n, \ n \in Z](https://tex.z-dn.net/?f=cosx%28sin%282x%29%2B1%29%3D0+%5C%5Ccosx%3D0+%5C%5Cx_1%3D%5Cfrac%7B%5Cpi%7D%7B2%7D%2B%5Cpi+n%2C%5C+n+%5Cin+Z+%5C%5Csin%282x%29%3D-1+%5C%5C2x%3D-%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+n%2C%5C+n+%5Cin+Z+%5C%5Cx_2%3D-%5Cfrac%7B%5Cpi%7D%7B4%7D%2B%5Cpi+n%2C+%5C+n+%5Cin+Z)
16 / 1,8 = x / 2,7 Высота здания относится к росту человека как тень здания - к тени человека