calculus
posted by Barbara .
the integral sign where 4 is on top and 2 is at the bottom (x/2 + 3)dx and im trying to find the areas to evaluate the intrgral

Compute the indefinite integral of(x/2) + 3.
It equals [x^2/4] + 3x
Subtract the value of that function at x=2 from the value at x=4. That will be the area under the curve. 
I got 7 but the answer in the book says 21

[x^2/4] + 3x at x= 4 is 16
[x^2/4] + 3x at x= 2 is 7
I get 9 for the answer.
Are you sure you copied the integrand correctly? Is it really (x/2) + 3 ?
I cannot explain the discrepancy