Question

alguém me ajuda?
(5x-2).(6x+1)=104

Answer 1

(5x-2).(6x+1)=104
3x.7x=104
21x=104
x=104/21
x=4,95

Answer 2

(5x-2).(6x+1)=104
30x^2 + 5x - 12x - 2 = 104
30x^2 - 7x - 2 - 104 = 0
30x^2 - 7x - 106 = 0
a= 30; b = - 7; c = - 106
∆ = b^2-4ac
∆ = (-7)^2 - 4.30.(-106)
∆ = 49 + 120.106
∆ = 49+12720
∆ = 12769
√∆= 113

x = [-b +/- √∆]/2a
x = [-(-7) +/- 113]/2.30
x' = [7+113]/60 = 120/60 = 2
x" = [7 - 113] / 60 = - 106/60 (:2) / (:2) = - 53/30

R.: {2 ; - 53/30}