what is the sum of the polynomials?\n(m + n + 3) + (m + n + 4)\n-1\nm² + n² + 7\n2m + 2n + 7\n2m² + 2n² + 7

Explanation:

Step1: Remove parentheses

Since there are plus - signs before the parentheses, the terms inside remain the same. So we have $m + n+3 + m + n + 4$.

Step2: Combine like - terms

Combine the $m$ terms: $m+m = 2m$. Combine the $n$ terms: $n + n=2n$. Combine the constant terms: $3 + 4 = 7$. The sum is $2m+2n + 7$.

Answer:

C. $2m + 2n+7$