Respuesta :

make the denominator into 10x:
5x/10x +20/10x=x(x+4)/10x
5x+20=x(x+4)
5x+20=x²+4x
x²-x-20=0
(x-5)(x+4)=0
x=5 or -4
the third choice is correct. 
To solve this complex fraction equation, we need to get the same denominator on the left, then combine them to one term. Then we can cross-multiply with the other side.
1/2 + 4/2x = x/2x + 4/2x = (x+4)/2x
Now we have (x+4)/2x = (x+4)/10
cross-multiply:
(x+4)×10 = (x+4)×2x
10x+40 = 2x^2+8x
[tex]2 {x}^{2} + 8x - 10x - 40 = 0 \\ 2 {x}^{2} - 2x - 40 = 0 \\ 2({x}^{2} - x - 20) = 0 \\ 2(x - 5)(x + 4) = 0 [/tex]
Therefore x = -4 and x = 5
C) is the correct answer
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