Question

$x2 = 4 \div 5x + 1 \div 5$

Answer 1

x^2 = 4x/5 + 1/5
5x^2/5 = (4x+1)/5
5x^2 = 4x + 1
5x^2 - 4x - 1 = 0
a= 5; b = - 4; c = - 1
∆ = b^2-4ac
∆ = (-4)^2 - 4.5.(-1)
∆ = 16 + 20
∆ = 36

x = [ - b +/- √∆]/2a
x = [-(-4)+/- √36]/2.5
x = [4 + 6]/10 = 10/10 = 1
x = [4 - 6]/10 = - 2/10 (:2)/(:2) = - 1/5

R.: ( 1 ; - 1/5)