5-3�ã2 multiplied by its conjugate is...

Its supposed to be 7, but I don't get how to do this, cause now im totally confused, i thought that the conjugate came when you were to rationalize a denominator...

I did this...

15�ã2-9�ã4
15�ã2-18

1 answer

Well, if you figure that 5^2 = 25, not 15, you'll be on your way