If X + Y = 9, Xy = 20 Find: X2 - Y2. - Mathematics

If x + y = 9, xy = 20
find: x² - y².

Sum

x + y = 9, xy = 20
We know (x - y) (x + y)
= x² - y²
⇒ x² - y²
= (±1) (9)
= ±9.

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