`1) 5(2x-1)+4(8-3x) =-5`
`<=> 10x -5 + 32 - 12x +5 =0`
`<=> -2x +32 =0`
`<=> -2x = -32`
`=> x= -32 : (-2) =16`
`2) 4x(x-1) -3(x^2 -5) -x^2 = x-3 -(x+4)`
`<=> 4x^2 -4x - 3x^2 +15 -x^2 = x-3-x-4`
`<=> -4x+15 = -7`
`<=> -4x = -22`
`x = -22 : (-4) = 11/2`
`3) 25x^2 -9 =0`
`<=>(5x)^2 -3^2 =0`
`<=>(5x-3)(5x+3)=0`
`<=> [(5x-3=0),(5x+3=0):}`
`<=> [(x=3/5),(x=-3/5):}`
`4)(2x-1)^2 +(x+3)^2 -5(x+7)(x-7) =16`
`<=> 4x^2 -4x +1 + x^2 + 6x +9 - 5(x^2 -49) -16 =0`
`<=> 5x^2 +2x +10 - 5x^2 + 245 -16 =0`
`<=> 2x + 239 =0`
`=> x = -239/2 = -119,5`
`5)3x(x-1) +x-1 =0`
`<=> (3x+1)(x-1) =0`
`<=> [(3x=-1),(x-1=0):}`
`<=> [(x=-1/3),(x=1):}`
1) 5(2x - 1) + 4(8 - 3x) = -5
10x - 5 + 32 - 12x = -5
-2x + 27 = -5
-2x = -5 - 27
-2x = -32
x = (-32) : (-2)
x = 16
Vậy x = 16
2) 4x(x - 1) - 3(x² - 5) - x² = x - 3 - (x + 4)
4x² - 4x - 3x² + 15 - x² = x - 3 - x - 4
-4x + 15 = -7
-4x = -7 - 15
-4x = -22
x = 22/4
x = 11/2
Vậy x = 11/2
3) 25x² - 9 = 0
(5x)² - 3² = 0
(5x - 3)(5x + 3) = 0
5x - 3 = 0 hoặc 5x + 3 = 0
*) 5x - 3 = 0
5x = 0 + 3
5x = 3
x = 3/5
*) 5x + 3 = 0
5x = 0 - 3
5x = -3
x = -3/5
Vậy x = -3/5; x = 3/5
4l(2x - 1)² + (x + 3)² - 5(x + 7)(x - 7) = 16
4x² - 4x + 1 + x² + 6x + 8 - 5x² + 195 = 16
2x + 204 = 16
2x = 16 - 204
2x = -188
x = -188/2
x = -94
`6)2(x+3) -x^2 -3x =0`
`<=> 2(x+3) -x (x +3) =0`
`<=> (2-x)(x+3) =0`
`<=> [(x=2),(x=3):}`
`7) x^3 +27 + (x+3)(x-9) =0`
`<=>(x+3)(x^2 -3x +9) + (x+3) (x-9) =0`
`<=> (x+3)(x^2 -3x +9 +x-9) =0`
`<=> (x+3)(x^2 -2x) =0`
`<=> x(x+3)(x-2) =0`
`<=> [(x=0),(x=-3),(x=2):}`
`8) x^3 -4x^2 +8x -32 =0 `
`<=> x^2 (x-4) + 8(x-4) =0`
`<=> (x^2 +8) (x-4) =0`
`<=>`\(\left[{}\begin{matrix}x^2=-8\\x-4=0\end{matrix}\right.\)
`=> x =4`
`9) x^2 -10x +16 =0`
`x^2 - 2x -8x +16 =0`
`<=> (x-2)(x-8) =0`
`<=> [(x=2),(x=8):}`
`10) x^3 -11x^2 +30x =0`
`<=> x(x^2 -11x +30 ) =0`
`Th1 :x =0`
`Th2 : x^2 -11x +30 =0`
`<=> (x-6)(x-5) =0`
`<=> [(x=6),(x=5):}`
