Question

Answer 1

8.

$(x+3)^2-(x-4)(x+8)=1$

$x^2+6x+9-(x^2+4x-32)=1$

$x^2+6x+9-x^2-4x+32=1$

$2x+41=1$

$2x=-40$

$x=-20$

Answer 2

7, \(\Leftrightarrow x^3-3.x^2.2+3.x.4-8-x^3+27+6\left(x^2+2x+1\right)-49=9\)

\(\Leftrightarrow x^3-6x^2+12x-8-x^3-22+6x^2+12x+6=0\Leftrightarrow24x-24=0\Leftrightarrow x=1\)

 

8, \(x^3+9x^2+27x+27-x^2-4x+32=1\)

\(\Leftrightarrow x^3+8x^2+23x+58=0\)

Answer 3

9, \(3x-x^3-1+x^3-4x=5\Leftrightarrow-x-1=5\Leftrightarrow x=-6\)

10, \(x^2-2x-24=0\Leftrightarrow\left(x-1\right)^2-25=0\Leftrightarrow\left(x-6\right)\left(x+4\right)=0\Leftrightarrow x=-4;x=6\)

Answer 4

7.

$(x-2)^3-(x-3)(x^2+3x+9)+6(x+1)^2=49$

$(x-2)^3-(x^3-3^3)+6(x^2+2x+1)=49$

$x^3-6x^2+12x-8-(x^3-27)+6x^2+12x+6=49$

$24x+25=49$

$24x=24$

$x=1$

Answer 5

9.

$3x-(x+1)(x^2-x+1)+x(x^2-4)=5$

$3x-(x^3+1)+(x^3-4x)=5$

$3x-x^3-1+x^3-4x=5$

$-x-1=5$

$-x=6$

$x=-6$

Answer 6

10.

$x^2-2x=24$

$x^2-2x-24=0$

$x^2-6x+4x-24=0$

$x(x-6)+4(x-6)=0$

$(x-6)(x+4)=0$

$\Rightarrow x-6=0$ hoặc $x+4=0$

$\Rightarrow x=6$ hoặc $x=-4$