In the term $-6a^3$, which number is the coefficient and which is the exponent?

A landscaper plants bed A with $3x^2+2x+1$ seedlings and bed B with $x^2+4x+3$ seedlings. Translate and find the total number of seedlings as a simplified polynomial.

Simplify $(4x^3+3x-5)+(-x^3+7-2x)$.

Compute $(-5m{)}^2$.

Compute $(2x-1)(2x+1)$.

Expand $(3x^2+4{)}^2$.