Question

Which expression represents the 4th term in the binomial expansion of (e+2f)^10

Answer 1

The answer depends on what is meant by the "fourth term". By the binomial theorem, one answer could be


`\dbinom{10}3e^3(2f)^(10-3)=120e^3(2f)^7=15360e^3f^7`

By symmetry, another could be


`\dbinom{10}3(2f)^3e^(10-3)=960e^7f^3`