Question

Решите систему уравнений: 3(х+у)+1=х+4у; 7-2(х-у)=х-8у.

Answer 1

3•( х + y ) + 1 = x + 4y
7 - 2•( x - y ) = x - 8y
Решение
3х + 3y + 1 = x + 4y
3x - x = 4y - 3y - 1
2x = y - 1
y = 2x + 1
7 - 2x + 2y = x - 8y
2y + 8y = x + 2x - 7
10y = 3x - 7
10•( 2x + 1 ) = 3x - 7
20x + 10 = 3x - 7
17x = - 17
x = - 1
y = 2•( - 1 ) + 1 = - 2 + 1 = - 1
Ответ ( - 1 ; - 1 )