Question

Resolva a seguinte Equação do segundo grau:x^2+x/5-x/15=11/5-x^2-9/15

Answer 1

x^2 + x/5 - x/15 = 11/5 - x^2 - 9/15 (:3)/(:3)
x^2 + x^2 + x/5 - x/15= 11/5 - 3/5
2x^2 + x/5 - x/15 = 8/5

MMC (5,15) = 15

(15.2x^2 + 3x - x)/15 = 3.8/15
30x^2 + 2x =24 (:2)
15x^2 + x = 12
15x^2 + x - 12 = 0
a= 15; b = 1; c = - 12
∆= b^2 - 4ac
∆ = 1^2 - 4.15(-12)
∆ = 1 + 720
∆ = 721

x = [- b +/- √∆]/2.a
x = [ - 1 +/- √721]/2.15

x' = [ - 1 + √721]/30
x" = [ - 1 - √721]/30