Question

find any real number for which the rational expression is undefined a-5/7

Answer 1

is it (a-5)/7 or a-(5/7)???

Answer 2

(a-5)/7

Answer 3

it's defined for all values of a..
if you were asking about \[7 \over a-5\]
then it would be undefined at
\[a-5=0 \implies a=5\]

Answer 4

so then answer would be 0 or 5?

Answer 5

the answer to your question would be "phi" (since there is no a where (a-5)/7 the expression undefined)

Answer 6

I meant by phi the empty set.. looks I am complicating things!! :)
you just need to know that the expression you gave is defined for all values of a. that's it

Answer 7

ok thanks