Question

Resolva a equação 4x – x(x – 2) = 5

Answer 1

4x-x^2+2x=5
(-1)-x^2+6x-5=0(-1)
x^2-6x+5=0
a=1 b=-6 c=5
x=6+- raiz de 36-20 / 2
x=6+- raiz de 16 / 2
x1=6+4/2=10/2=5
x2=6-4/2=2/2=1
S={5,1}

Answer 2

4x – x(x – 2) = 5
4x - x² + 2x = 5
6x - x² = 5
0 = x² - 6x + 5
x² - 6x + 5 = 0
a = 1; b = - 6; c = 5

Δ = b² - 4ac
Δ = (-6)² - 4.1.5
Δ = 36 - 20
Δ = 16

x = - b +/- √Δ  = - ( - 6) +/- √16
           2a                2.1

x' = 6 + 4 = 10/2 = 5
        2

x" = 6 - 4 = 2/2 = 1
        2

R.: x = 5 e x = 1