Question

21=7x ao quadrado utilizando bháskara

Answer 1

Resposta:

21=7x²

7x²-21=0 (÷7)

x²-3=0

$Aplicando~a~f\'{o}rmula~de~Bhaskara~para~x^{2}-0x-3=0~~\\e~comparando~com~(a)x^{2}+(b)x+(c)=0,~temos~a=1{;}~b=0~e~c=-3\\\\\Delta=(b)^{2}-4(a)(c)=(0)^{2}-4(1)(-3)=0-(-12)=12\\\\x^{'}=\frac{-(b)-\sqrt{\Delta}}{2(a)}=\frac{-(0)-\sqrt{12}}{2(1)}=\frac{0-2\sqrt{3}}{2}=-\frac{2\sqrt{3}}{2}=-\sqrt{3}\\\\x^{''}=\frac{-(b)+\sqrt{\Delta}}{2(a)}=\frac{-(0)+\sqrt{12}}{2(1)}=\frac{0+2\sqrt{3}}{2}=\frac{2\sqrt{3}}{2}=\sqrt{3}\\\\S=\{-\sqrt{3},~\sqrt{3}\}$