Question

Calcule -x² + 13x - 42= 0

( ) x' = -7 x"= 6

( ) x'= -7 x"= -6

( ) x'= 6 x" = 7

( ) x'= 6 x" = -7

( ) x'= -6 x" = 7​

Answer 1

-x+13x-42=0

primeiro vamos calcular o delta

∆=b²-4.a.c

∆=13²-4.-1.-42

∆=169-168

∆=1

usando a fórmula de Bhaskara

x= -b ± √∆/2.a

x= -13 ± √1/2.(-1)

x'= -13+ 1/-2

x'=-12/-2

x'=6

x"= -13-1/-2

x"= -14/-2

x"= 7

letra(c) x'= 6 x" = 7