Question

as soluções da equação (x+3)(2x-4)=0, são:
a) 2 e 3
b) 3 e 4
c) -3 e 4
D) -3 e 2 ​

Answer 1

(x+3)(2x-4)=0 ↓

=> (x+3)=0 => x'= -3 ✓

=> (2x-4)=0=> 2x=4 => x"= 2 ✓

====> D) -3 e 2

Bhaskarando

(x+3)(2x-4)=0

2x²-4x +6x-12=0

2x² +2x -12=0 ==> :(2)

x² +x -6 = 0

∆= b²-4ac= 1² +24=25 ==> √∆=5

x= -b+√∆/2a = -1+5/2 = 4/2 = 2

x"= -b-√∆/2a = -1-5/2= -6/2 = -3