Question

qual é o valor de x na pg (-2,x+1,-4x+2)

Answer 1

$a1=-2\\a2=x+1\\\\q=\frac{a2}{a1}=\frac{x+1}{-2}\\\\a3=-4x+2\\\\an=a1.q^{n-1}\\a3=a1.(\frac{x+1}{-2})^2\\-4x+2=-2.\frac{x^2+2x+1}{4}\\-4x+2=\frac{-x^2-2x-1}{2}\\-8x+4=-x^2-2x-1\\x^2+2x+1-8x+4=0$

$\\x^2-6x+5=0\\\Delta=b^2-4ac=36-4.1.5=16\\x=\frac{-b\pm\sqrt{\Delta}}{2a}\\\\\boxed{x'=\frac{6+4}{2}=5}\\\\\\\boxed{x''=\frac{6-4}{2}=1\\}$