Help meeeee giúp vs a/ x^2-(x+3)(3x+1)=9 b/ x^2+4x+5=0 c/ (x+14)^2 -(x+12)^2= 1352 d/ x^2+ (x-3)^2= (2x-3)^2 e/ x(x+1)(x+2)(x+3)=360 f/ x^2+ (x-2)(2x+1)=8

`a, x^2 - (x + 3)(3x + 1) = 9`

`⇔ x^2 - 9 - (x + 3)(3x + 1) = 0`

`⇔ (x + 3)(x - 3) - (x + 3)(3x + 1) = 0`

`⇔ (x + 3)(x - 3 - 3x - 1) = 0`

`⇔ (x + 3)(-2x - 4) = 0`

`⇔ -2(x + 3)(x + 2) = 0`

`⇔ (x + 3)(x + 2) = 0`

`⇔` $\left[ \begin{array}{l}x+3=0\\x+2=0\end{array} \right.$ `⇔` $\left[ \begin{array}{l}x=-3\\x=-2\end{array} \right.$ 

`b, x^2 + 4x + 5 = 0`

`⇔ (x^2 + 4x + 4) + 1 = 0`

`⇔ (x + 2)^2 = -1`

Mà `(x + 2)^2 ≥ 0`

`⇒ x ∈ ∅`

`c, (x+14)^2 - (x + 12)^2 = 1352`

`⇔ x^2 + 28x + 196 - x^2 - 24x - 144 = 1352`

`⇔ 4x = 1300`

`⇔ x = 325`

`d, x^2 + (x-3)^2 = (2x - 3)^2`

`⇔ x^2 + x^2 - 6x + 9 = 4x^2-12x+9`

`⇔ -2x^2 + 6x = 0`

`⇔ -2x(x - 3)` = 0`

`⇔ x(x - 3) = 0`

`⇔` $\left[ \begin{array}{l}x=0\\x-3=0\end{array} \right.$ `⇔` $\left[ \begin{array}{l}x=0\\x=3\end{array} \right.$ 

`e, x(x+1)(x+2)(x+3) = 360`

`⇔ x^4+3x^3+2x^3+6x^2+x^3+3x^2+2x^2+6x=360`

`⇔ x^4+6x^3+11x^2+6x-360=0`

`⇔ (x^2+3x+20)(x+6)(x-3)=0`

`⇔ $\left[ \begin{array}{l}x=-6\\x=3\end{array} \right.$ 

`f, x^2+ (x-2)(2x+1)=8`

`⇔ x^2 + 2x^2 + x - 4x - 2 - 8 = 0`

`⇔ 3x^2 + 3x - 10 = 0`

`⇔ x = -\frac{3-\sqrt{129}}{6}; x = -\frac{3+\sqrt{129}}{6}`