Answer:
x^2 + y^2 = 9
What is the difference of square formula (a ^ 2 - b ^ 2)?
It is used to find the difference between the two squares without actually calculation the square.
a^2 - b^ 2 = (a-b) (a +b)
x^4 - y^4 = 45
(x^2)^2 - (y ^2) ^ 2 = 45
(x^2 - y^ 2) (x^2 + y^2) = 45
5 (x^ 2 + y ^ 2) =45
x^2 + y^2 = 9
correct option is A ) 9
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