Question

-x² +10x - 21 = 0 Qual é o valor de x1 e x2?

Answer 1

a= -1

b= 10

c= -21

 

delta = 10² - 4 . -1. -21 = 100 - 84 = 16

 

x1 = (- 10 + raiz de 16 )/ -2 = (-10 + 4)/-2= -6/-2= 3

x2 = ( -10 - raiz quadrada de 16)/-2 =  -14/-2 = 7

 

 

Answer 2

$-\text{x}^2+10\text{x}-21=0$

 

$\text{x}=\dfrac{-10\pm\sqrt{10^2-4\cdot(-1)\cdot(-21)}}{2\cdot(-1)}=\dfrac{-10\pm4}{-2}$

 

$\text{x}_1=\dfrac{-10+4}{-2}=3$

 

$\text{x}_2=\dfrac{-10-4}{-2}=7$