Question

F=x2/1+x2 find range

Answer 1

I don't know.........

Answer 2

$let \: \: y = \frac{ {x}^{2} }{1 + {x}^{2} } \\ \\ \\ y(1 + {x}^{2} ) = {x}^{2} \\ \\ \\ y + {x}^{2}y = {x}^{2} \\ \\ \\ {x}^{2} - {x}^{2} y = y \\ \\ \\ {x}^{2} (1 - y) = y \\ \\ \\ {x}^{2} = \frac{y}{1 - y} \\ \\ \\ x = \sqrt{ \frac{y}{1 - y} } \\ \\ \\ y < 1 \\ \\ \\ range = ( \infty \: \: 1)$

THANKS