I got 2 right but please explain why 5 why not 4 ? are you counting all the possible prime implicants possible or you're simply solving the question by simply making pairs and then counting

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here 5 prime implicants

and I and V are essential prime implicants

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Magma why you're making 2nd prime implicant when all 1s of 1st and 2nd pairs are grouped ?

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because we need to consider all combination of pairs.

some additional info that I found very helpful:

Prime implicants
all possible combinations of minterms with preference from oct then quad then pair.
eg. if quad possible then don't try internal pair and assume they are also prime implicants

Essential prime implicants:
There is at least a one min term in octet,quad,pair which is not covered by any other prime
implicant.