1)ОДЗ: x≠-8
2)x³+7x = 8
x³+7x-8 = 0
x³-x+8x-8 = 0
x(x²-1)+8(x-1) = 0
x(x-1)(x+1)+8(x-1) = 0
(x-1)(x(x+1)+8) = 0
(x-1)(x²+x+8) = 0
1°)x1 = 1
2°)x²+x+8 = 0
D = b²-4ac = 1-4•8 < 0
∅
ответ: x = 1
1)ОДЗ: x≠-8
2)x³+7x = 8
x³+7x-8 = 0
x³-x+8x-8 = 0
x(x²-1)+8(x-1) = 0
x(x-1)(x+1)+8(x-1) = 0
(x-1)(x(x+1)+8) = 0
(x-1)(x²+x+8) = 0
1°)x1 = 1
2°)x²+x+8 = 0
D = b²-4ac = 1-4•8 < 0
∅
ответ: x = 1