Question 175861
(5z-2)(5z+2)....use foil
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F: 5z*5z = 25z^2
O: 5z*2  = 10z
I: 5z*-2 =-10z
L: -2*2  = -4
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Combine the four results to get:
25z^2 - 4
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Cheers,
Stan H.