Answer:
6x^3+3x^2
Step-by-step explanation:
Volume is b*h*w.
So, we have (3x)(x)(2x+1).
Simplifying the parentheses, we get: 3x*x*(2x+1).
3x*x= 3x^2.
Now we can simplify the other parentheses.
3x^2(2x+1) will be 6x^3+3x^2, because (3x^2)(2x)+(3x^2)(1).
Thus, we get 6x^3+3x^2