Question

x supra 1 - x = 4 + x supra x - 3

Answer 1

x(x-3)=(1-x)(4+x)
x²-3x=4+x-4x-x²
x²+x²-3x-x+4x-4=0
2x²-4=0

Answer 2

$\frac{x}{1-x}= \frac{4+x}{x-3}=> x^{2} -3x=(1-x)(4+x)=> x^{2} -3x=4+x-4x- x^{2} \\ => x^{2} -3x=4-3x- x^{2} =>-2 x^{2} =4=> x^{2} =-2=>x=- \sqrt{2}$