Question

conjunto solução x(x+11)+2(x+21)

Answer 1

x² + 11x + 2x + 42 =0

x² + 13x + 42

Answer 2

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

Podemos resolver por Bhaskára:
Delta= b²-4ac
Delta=169-168
Delta=1

x= -13√1/2
x=-13±1/2

x'=-7
x''= -6

Assim, S={-7,-6}.