<h3>ctg( - 660° ) = - ctg( 660° ) = - ctg( 720° - 60° ) = - ( - ctg60° ) = ctg60° = √3/3</h3><h3><em><u>ОТВЕТ: √3/3</u></em></h3><h3><em><u /></em></h3>
А.3х+3+7х-21=8ҳ+16
2х=34
х=17
б.4х-4+6х+12=8х-24
2х=-24-8
2х=-32
х=-16
6y - 6y - 5x - 5x = 70 - 50
- 10x = 20
x = - 2
6y + 10 = 70
y = ( 70 - 10 ) : 6
y = 10
ОТВЕТ ( - 2 ; 10 )
4х + 4х + 9y - 9y = 20 - 52
8x = - 32
x = - 4
- 16 + 9y = 20
y = ( 20 + 16 ) : 9
y = 4
ОТВЕТ ( - 4 ; 4 )
6х + 6х - 7y + 7y = - 14 + 98
12x = 84
x = 7
42 + 7y = 98
y = ( 98 - 42 ) : 7
y = 8
ОТВЕТ ( 7 ; 8 )