Question

b) (x2+ 9x +20)= (x +5 )



ajudaaaaa por favor???​

Answer 1

Resposta:

S={x∈|R/x= -5 ou x= -3}

Explicação passo-a-passo:

x²+9x+20=x+5

x²+9x-x+20-5=0

x²+8x+15=0

$\displaystyle Aplicando~a~f\'{o}rmula~de~Bhaskara~para~x^{2}+8x+15=0~~e~comparando~com~(a)x^{2}+(b)x+(c)=0,~determinamos~os~coeficientes:~\\a=1{;}~b=8~e~c=15\\\\C\'alculo~do~discriminante~(\Delta):&\\&~\Delta=(b)^{2}-4(a)(c)=(8)^{2}-4(1)(15)=64-(60)=4\\\\C\'alculo~das~raizes:&\\x^{'}=\frac{-(b)-\sqrt{\Delta}}{2(a)}=\frac{-(8)-\sqrt{4}}{2(1)}=\frac{-8-2}{2}=\frac{-10}{2}=-5\\\\x^{''}=\frac{-(b)+\sqrt{\Delta}}{2(a)}=\frac{-(8)+\sqrt{4}}{2(1)}=\frac{-8+2}{2}=\frac{-6}{2}=-3\\\\S=\{-5,~-3\}$