Question

Quanto é (x+3)²=(2x+1)² ?

Answer 1

$x^{2} + 9=4 x^{2} +4x+1 \\ 3x^{2} +4x-8=0$

Δ=$4^{2} -4.(-8).4= 16+128=144$

$x'= \frac{-4+ \sqrt{144} }{6} = \frac{-4+12}{6} = \frac{8}{6} = \frac{4}{3} \\ x"= \frac{-4- \sqrt{144} }{6} = \frac{-4-12}{6}= \frac{-16}{6}$