2+ – 2c+ – 9c^2
what is the answer

Replace all occurrences of + − with a single − . A plus sign followed by a minus sign has the same mathematical meaning as a single minus sign because 1 ⋅ − 1 = − 1 2 − 2 c − 9 c 2

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents