Question

Resolva a equação x (x+11)+2 (x+21)=0

Answer 1

x(x+11)+2(x+21)=0
x²+11x+2x+42=0
x²+13x+42=0

equação do 2° grau
formula para delta.
delta=b²-4.a.c onde:

a=1, b=13, c=42

delta=13²-4.1.42
delta=169-168
delta=1

x=-b±√delta/2.a

x=-13±√1/2.1

x=-13±1/2

x=-13+1/2 = -12/2= -6

x=-13-1/2= -14/2= -7

s{-6,-7}