Question

Cuál es la incógnita de m al cuadrado+10m+21=0

Answer 1

m² + 10m +21 = 0

(m + 7)(m+3)= 0

m +7 = 0 => m = - 7

m +3 = 0 => m = - 3

Answer 2

${m^2+10m+21=0}\\{\downarrow\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \downarrow}\\{m\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 7}\\{m\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3}\\\\{(m+3)(m+7)=0}\\\\\\{m+3=0}\\\\{\boxed{m_1=-3}}\\\\\\{m+7=0}\\\\{\boxed{m_2=-7}}$


Salu2.!! :)
Wellington