210/х-210/х+10=1/2
(210/х)*2 - (210/х)*2+10*2х-(1/2)*х=0
(420-420+20х-х)/2х=0
19х=0; х=0
2х=0: х=0
7х - 9у = 128
х = - у
7 * (-у) - 9у = 128
- 7у - 9у = 128
- 16у = 128
у = 128 : (-16)
у = - 8
х = - (-8)
х = 8
Ответ : ( 8 ; - 8) .
15-p=1/3p-1
-p - 1/3p = -1 - 15
- 4/3p = -16
p = - 16/1 : (-4/3)
p = 12
sin(x)+sin(3x)+cos(x)+cos(3x)=0