Simplify the expression completely (9-5 4√6)(7- 4√8).
Not sure just what
(9-5 4√6)
means.
But, let's ignore the 5 for now and pretend you had
(9-4√6)(7- 4√8)
Just expand like any polynomial:
9*7 - 4√6*7 - 9*4√8 + 4√6*4√8
63 - 28√6 - 36√8 + 16√48
Pulling out all the perfect squares, we are left with
63 - 28√6 - 72√2 + 64√3
Not sure just how much you want to massage all that.