Ответы
Ответ:
1) x = -0,625
2) x = 0,5
3) x = -3,5
4) x = +-10
5) -1 и 5 / 6
6) [ -5 ; -0,3 ]
7) x < 12
Объяснение:
1) 0,6x = -3 / 8
x = ( -3 / 8 ) : 0,6
x = ( -3 / 8 ) : 6 / 10
x = ( -3 / 8 ) : 3 / 5
x = ( -3 / 8 ) * 5 / 3
x = -5 / 8
x = -0,625
2) 4x - 1 = 2x
4x - 2x = 1
2x = 1
2x ( :2 ) = 1 : 2
x = 0,5
3) 5 + 3 ( x - 4 ) = 5x
5 + 3x - 12 = 5x
3x - 5x = 12 - 5
-2x = 7
-2x : ( -2 ) = 7 : ( -2 )
x = 3,5
4) x^2 - 100 = 0
x^2 = √100
x = +-10
5) 6x^2 + x -5 = 0
D = b^2 - 4ac = 0
1^2 - 4 * 6 ( -5 ) = 1 + 120 = 121 ( 121 > 0, значит 2 корня )
x1 = ( - 1 - √121 ) / ( 2 * 6 ) = ( -1 - 11 ) / 12 = - 12 / 12 = - 1
x2 = ( -1 + √121 ) / ( 2 * 6 ) = ( -1 + 11 ) / 12 = 10 / 12 = 5 / 6
6) | -2x < 10
| 5x > -1,5
| -2x : ( -2 ) < 10 : ( -2 )
| 5x ( :5 ) > -1,5 : 5
| x > -5
| x > -0,3
[ -5; -0,3 ]
7) -8 ( x - 2 ) > 4 - 7x
-8x + 16 > 4 - 7x
-8x + 7x > 4 - 16
-x > -12
-x : ( -1 ) > -12 : ( -1 )
x < 12