Respuesta :

-18

You get [ a^2 - b^2 ] by multiplying the other 2 equations together using FOIL:

(a + b) (a - b) = a^2 - ab + ab - b^2 = a^2 - b^2

So:
6 (-3) = -18

Because it tells you a+b is 6 and a-b is -3

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