Question

X ao quadrado -10x + 21 =0

Answer 1

x^2-10x+21

b^2-4ac
10^2-4.1.21 = 16
-b+-raiz de delta/2a
-(-10)+- raiz de 16/2.1
10+-4/2 
x'=7
x''=3

Answer 2

x²-10x+21 = 0

Δ= (-10)²-4.1.21
Δ= 100- 84
Δ= 16

x= - (-10)+-√16/ 2.1
x = 10 + - 4/ 2

x'= 10 + 4/ 2= 14/2 = 7
x''= 10- 4/2 = 6/2 = 3