Question

Bài 2: Tìm x biết:

1,x\(^2\)+4x+4=25

2,(5-2x)\(^2\)-16=0

3,(x-3)\(^3\)-(x-3)(x\(^2\)+3x+9)+9(x+1)\(^2\)=15

4,3(x+2)\(^2\)+(2x-1)\(^2\)-7(x-3)9x+3)=36

5,(x-3)(x\(^2\)+3x+9)+x(x+2)(2-x)=1

6,(2x+1)\(^2\)-4(x+2)\(^2\)=9

7,(x+3)\(^{^{ }2}\)-(x-4)(x+8)=1

Answer 1

1: =>x^2+4x-21=0

=>(x+7)(x-3)=0

=>x=3 hoặc x=-7

2: =>(2x-5-4)(2x-5+4)=0

=>(2x-9)(2x-1)=0

=>x=9/2 hoặc x=1/2

3: =>x^3-9x^2+27x-27-x^3+27+9(x^2+2x+1)=15

=>-9x^2+27x+9x^2+18x+9=15

=>18x=15-9-27=-21

=>x=-7/6

6: =>4x^2+4x+1-4x^2-16x-16=9

=>-12x-15=9

=>-12x=24

=>x=-2

7: =>x^2+6x+9-x^2-4x+32=1

=>2x+41=1

=>2x=-40

=>x=-20