Question

What property of real numbers be for 9/4 • 4/9=1

Answer 1

That would be the inverse property of multiplication. What the inverse property says is that, for every real number
`a`, there is some special number
`a^(-1)` out there called the multiplicative inverse, which has the property that

`a\cdot a^(-1)=1`

In this case,
`a=(9)/(4)` and its inverse
`a^(-1)=(4)/(9)`