5.(x + 3) - x^2 - 3x = 0
5.(x + 3) - x.(x + 3) = 0
(x + 3).(5 - x) = 0
TH1: x + 3 = 0
x = -3
TH2: 5 - x = 0
x = 5
=> x thuộc {-3 ; 5}
(x - 3).(x^2+ 3x + 9) + x.(x + 1).(1 - x) = 0
x^3 - 27 - x.(x + 1).(x - 1) = 0
x^3 - 27 - x.(x^2 - 1) =0
x^3 - 27 - x^3 + x = 0
(x^3 - x^3) - 27 + x = 0
- 27 + x = 0
x = 27
2x^2 - (x - 1).(x + 1) = 2
2x^2 - x^2 + 1 = 2
(2x^2 - x^2) + 1 = 2
x^2 + 1 = 2
x^2 = 1
x = 1
x^2 - 10 = 25
x^2 = 25 + 10
x^2 = 35
x = căn bậc 35
x.(2x - 1).(x + 5) - (2x^2 + 1).(x + 4,5) = 3,5
2x^3 + 10x^2 - x^2 - 5x - 2x^3 - 9x^2 - x - 4,5 = 0
(2x^3 - 2x^3) + (10x^2 - x^2 - 9x^2) - (5x + x) - 4.5 = 0
- 6x - 4,5 = 0
-6x = 4,5
x = 4,5 : -6
x = - 0,75
(3x^2 - x + 1).(x - 1) + x^2.(4 - 3x) = 5/2
3x^3 - 4x^2 + 2x - 1 + 4x^2 - 3x^3 = 5/2
(3x^3 - 3x^3) - (4x^2 - 4x^2) + 2x - 1 = 5/2
2x - 1 = 5/2
2x = 7/2
x = 7/2 : 2
x = 7/4
#chucbanhoctotnhe:33
