Question

(io) (5-✓2)(5+✓2)
How is this a rational number? can someone plz explain it to me​

Answer 1

it is a rational no as

it is in form of (a-b)(a+b)

and we know that

a²-b²=(a-b)(a+b)

therefore,

(5-√2)(5+√2)=(5)²-(√2)²

=25-2

=23

which is a rational no