I. Способ подстановки.1) 4x - 3y = -1 x - 5y = 4 x = 5y + 4 подставляем в 1-е ур-ние 4*(5у+4) - 3у = -1 20у + 16 - 3у = -1 17у = -17 у = -1 Подставляем значение у во 20-е ур-ние: х - 5(-1) = 4 х + 5 = 4 х = -12) x + 2y = -2 x = -2- 2y 3x - y = 8 3*(-2-2y) - y = 8 -6 -6y - y = 8 -7y = 14 y = -2 x = -2- 2y x = -2 -2(-2) = -2+4 = 23) x - y = 3 x = 3 + y 3x + 4y = 2 3(3+y) +4y = 2 9 + 3y + 4y = 2 7y = -7 y = -1x = 3 + yx = 3 + (-1) = 2II. Способ сложения1) 4x - 3y = -1 x - 5y = 4 *-4 -4x + 20y = -164x - 3y = -1
-4x + 20y = -164x - 3y -4x + 20y = -1 + (-16) 17y = - 17 y = -1x - 5y = 4x - 5*(-1) = 4x +5 = 4x = -12) x + 2y = -2 3x - y = 8 *2 x + 2y = -2
6x - 2y = 16x + 2y + 6x - 2y = -2 + 167x = 14x = 2x + 2y = -22 + 2y = -22y = -4y = -23) x - y = 3 *4 3x + 4y = 2
4x - 4y = 12 3x + 4y + 4x - 4y = 2 + 12 7x = 14x = 22 - y = 3-y = 1y = -1