Given:
The volume of the rectangular prism is
,
the height is h=(b+3)
1. The volume of a rectangular prism is (base area)*height
also, notice that the volume is a third degree polynomial, the height is a 1st degree polynomial, so the base area must be a 2nd degree polynomial, whose coefficients we don't know yet.
Let this quadratic polynomial be
2
notice that
is the product of the largest 2 terms: 
and b, so m must be 1
also, notice that 12 is the product of the constants, k and 3
so k*3=12, this means k=4
3
we write the above equality again:
=
4
now compare the coefficient with the left side:
8=n+3
n=5
substituting n=5:
the base area is
Answer:
The volume of the rectangular prism is
the height is h=(b+3)
1. The volume of a rectangular prism is (base area)*height
also, notice that the volume is a third degree polynomial, the height is a 1st degree polynomial, so the base area must be a 2nd degree polynomial, whose coefficients we don't know yet.
Let this quadratic polynomial be
2
notice that
also, notice that 12 is the product of the constants, k and 3
so k*3=12, this means k=4
3
we write the above equality again:
=
4
now compare the coefficient with the left side:
8=n+3
n=5
substituting n=5:
the base area is
Answer: