Đáp án+Giải thích các bước giải:
`9) (x+5)^2-6=0`
`<=> (x+5)^2 = 6`
`<=> (x+5)^2 = (±\sqrt{6})^2`
`<=> x+5 = ±\sqrt{6}`
`<=> x = ±\sqrt{6}-5`
Vậy `x∈{±\sqrt{6}-5}`
`10) (x+3)(x^2-3x+9)-x^3=2x`
`<=> x^3 + 27 - x^3 -2x =0 `
`<=> (x^3-x^3)-2x=0-27`
`<=> -2x = -27`
`<=> x = (27)/2`
Vậy `x=(27)/2`
`11) 3x(2x-7)+2x(5-3x) =5`
`<=> 6x^2 - 21x + 10x-6x^2=5`
`<=> (6x^2-6x^2)-(21x-10x)=5`
`<=> -11x = 5`
`<=> x = -5/(11)`
Vậy `x = -5/(11)`
`12) 0,6x(x-0,5)-0,3x(2x+1,3)=0,38`
`<=> 0,6x^2 - 0,3x-0,6x^2-0,39x = 0,38`
`<=> -0,69x = 0,38`
`<=> x = -(38)/(69)`
Vậy `x = -(38)/(69)`
`13) (x-2)^3 -x^3+6x^2=7`
`<=> x^3 - 6x^2 + 12x-8-x^3+6x^2=7`
`<=> 12x = 15`
`<=> x = 5/4`
Vậy `x= 5/4`
`14) 6x^2-(2x+5)(3x-2)=7`
`<=> 6x^2-(6x^2-4x+15x-10)=7`
`<=> 6x^2-6x^2 +4x-15x +10=7`
`<=> -11x = -3`
`<=> x = 3/(11)`
Vậy ` x = 3/(11)`
`15) (2x-1)(3x+1)+(3x-4)(3-2x)=5`
`<=> 6x^2+2x-3x-1+9x-6x^2-12+8x=5`
`<=> 16x = 18`
`<=> x = 9/8`
Vậy `x = 9/8`
