Question

5u exponent 7 - 21u exponent 7

Simply

Answer 1

Assuming the given is: 5u^7 - 21u^7
Since both algebraic terms are identical (both are using u^7), we can subtract the coefficients directly, as in: 5 - 21 = -16
Therefore, 5u^7 - 21u^7 = -16u^7