Answer:
B, C
Step-by-step explanation:
The values of the expressions are ...
A:
20^2 -18^2 = (20 -18)(20 +18) = 2·38 = 4·19 ≠ 12^2 = 4·36
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B:
8(4^2) +2^4 = 8(4^2) +4^2 = (8+1)·4^2 = (3·4)^2 = 12^2
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C:
15^2 -3^4 = 15^2 -9^2 = (15 -9)(15 +9) = 6·24 = 6·2·12 = 12^2
