Х+5≥1-3х
х+3х≥1-5
4х≥-4
х≥-1
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-----------*-------------->x
-1
Ответ: х∈[-1; +∞)
20x² + x - 12 = 0D = b² - 4ac = 1 - 4×20×(-12)= 1 + 960 = 961 = 31²x1 = ( - 1 + 31) / 40 = 30/40 = 0,75x2 = ( - 1 - 31) / 40 = - 32/40 = - 0,8 - отрицательный корень.
дальше сам долго писать ато
( z + v )/15 - ( z - v )/3 = 1
Z + v - 5( z - v ) = 15
z + v - 5z + 5v = 15
6v - 4z = 15
••••••••••••••
( 2z - v )/6 - ( 3z + 2v )/3 = - 25
2z - v - 2( 3z + 2v ) = - 25•6
2z - v - 6z - 4v = - 150
- 5v - 4z = - 150
•••••••
5v + 4z = 150
6v - 4z = 15
11v = 165
v = 15
6•15 - 4z = 15
4z = 90 - 15
z = 75 : 4
z = 18,75
Ответ
z = 18,75
v = 15