X+2y=4 5x+8y=-1 4х-у=4 5х-2у=11 9х+2у=16 3х-5у=11 - вопрос №55202142458144521192163511 от bkmz987 10.05.2020 13:15

Question

Алгебра: X+2y=4 5x+8y=-1 4х-у=4 5х-2у=11 9х+2у=16 3х-5у=11

bkmz987 · Answer

N 1
x + 2y = 4
x = 4 - 2y
5x + 8y = - 1
5•( 4 - 2y ) + 8y = - 1
20 - 10y + 8y = - 1
- 2y = - 21
y = 10,5
x = 4 - 2•10,5 = - 17
ответ ( - 17 ; 10,5 )
N 2
4x - y = 4
y = 4x - 4
5x - 2y = 11
5x - 2•( 4x - 4 ) = 11
5x - 8x + 8 = 11
- 3x = 3
x = - 1
y = - 4 - 4 = - 8
ответ ( - 1 ; - 8 )
N 3
9x + 2y = 16
3x - 5y = 11
- 9x + 15y = - 33
17y = - 17
y = - 1
3x + 5 = 11
x = ( 11 - 5 ) : 3 = 2
ответ ( 2 ; - 1 )