Question

why are these two equations equal

Answer 1

\[\frac{ u ^{2}}{ 1+u^2 } = 1 - \frac{ 1 }{ 1+u^2 }\]

Answer 2

basic algebra i'm sure. just drawing a blank here.

Answer 3

you have to take the common denominator

Answer 4

just like how you need common denominator to add fractions now your denominator just happens to be some expression instead of a number