Question

Решите уравнение (х-2) ^3 - (х-3) ^3 = 27

Answer 1

$\left(x-2\right)^3-\left(x-3\right)^3=27\medskip\\\left(x-2-x+3\right)\left(\left(x-2\right)^2+\left(x-2\right)\left(x-3\right)+\left(x-3\right)^2\right)=27\medskip\\x^2-4x+4+x^2-5x+6+x^2-6x+9=27\medskip\\3x^2-15x+19=27\medskip\\3x^2-15x-8=0\medskip\\x_{1,2}=\dfrac{15\pm\sqrt{225+96}}{6}=\dfrac{15\pm\sqrt{321}}{6}\medskip\\\left[\begin{gathered}x=\dfrac{15+\sqrt{321}}{6}\\x=\dfrac{15-\sqrt{321}}{6}\end{gathered}$

ответ. $x=\dfrac{15+\sqrt{321}}{6}\,;\,x=\dfrac{15-\sqrt{321}}{6}$