Question

решите методом подстановки систему 3х+у=2 х-2у=7

Answer 1

3x+y=2
x-2y=7

y=2-3x
x-4+6x=7
7x=11
x=11/7

y=2-3*11/7
y=2-33/7
y=-19/7

Answer 2

x=-3/5

Answer 3

y=19/5

Answer 4

3X + Y = 2 
X - 2Y = 7 
-------------
X = 2Y + 7 
3 * ( 2Y + 7) + Y = 2 
6Y + 21 + Y = 2 
7Y = - 19 
Y = - 19/7 = - 2 ( 5/7 ) 
X = 2 * ( - 19/7 ) + 7 = - 38/7 + 7 = - 5 ( 3/7 ) + 7 = 1 ( 4/7 ) 

Answer 5

3х+у=2 х+2у=7

Answer 6

прости знак перепутала