Student X claims that $4x^2$ and $4x$ can be combined into $8x^2$ because they "both have $x$". Evaluate this claim and choose the best justification.

Simplify the sum of three polynomials: $(2x^2+x-3)+(-x^2+4x+5)+(x^2-6x-2)$.

Simplify and evaluate the polynomial $(2x^2-3x+5)+(-x^2+4x-2)$ at $x=2$.

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

Factor $36x^2-25$ completely over the integers.

Expand ${\left(\frac{1}{2}x+3\right)}^2$.