Question

a-)$x^{2} -x-20=0$ b-) 23x-16=14-17x
Aguém pode me ajudar,por favor

Answer 1

Olá, boa tarde!


(a) Vamos utilizar a fórmula de Bhaskara.
$x^2-x-20=0\\\\Coeficientes:\;a=1,\;b=-1\;e\;c=-20\\\\\Delta=b^2-4ac\\\Delta=(-1)^2-4\cdot1\cdot(-20)\\\Delta=1+80\\\Delta=81\\\\x=\dfrac{-b\pm\sqrt{\Delta}}{2a}\\\\x=\dfrac{-(-1)\pm\sqrt{81}}{2\cdot1}\\\\x=\dfrac{1\pm9}{2}\\\\x_1=\dfrac{1+9}{2}=\dfrac{10}{2}=5\\\\x_2=\dfrac{1-9}{2}=\dfrac{-8}{2}=-4$


(b) 23x - 16 = 14 - 17x
23x + 17x = 14 + 16
40x = 30
x = 30/40
x = ¾


Espero ter ajudado.
Bons estudos! :)