Х3-49х=0 7х2=(2х+1)2+3х2-5 (х-2)3+(х+2)3=2х(х2-1)+3

[latex]x^3-49x=0\\ x(x^2-49)=0\\ x_1=0, x_{2,3}=\pm7\\\\ 7x^2=(2x+1)^2+3x^2-5\\ 7x^2=4x^2+4x+1+3x^2-5\\ 7x^2-7x^2-4x+4=0\\ 4x=4\\ x=1\\\\ (x-2)^3+(x+2)^3=2x(x^2-1)+3\\ (x-2+x+2)((x-2)^2+(x-2)(x+2)+(x+2)^2) \\2x(x^2-4x+4+x^2-4+x^2+4x+4)-2x(x^2-1)=3\\ 2x(3x^2+4-x^2+1)=3\\ 2x(2x^2+5)-3=0\\ 4x^3+10x-3=0\\ D=10^2+4*4*3=100+48=148\\ x_{1,2}=\frac{-10\pm2\sqrt{37}}{8}=\frac{-5\pm \sqrt{37}}{4}[/latex]