Answer:
[tex]\int k(x + 18)dx = \int kx + 18k dx[/tex] = [tex]k\frac{x^{2} }{2}[/tex] + [tex]18kx[/tex] + C where C is the constant of integration.
Step-by-step explanation:
i)it is given that the rate of change of W with respect to x is proportional to
x + 18. Therefore [tex]\frac{dW}{dx}[/tex] = k(x + 18) where k is a constant.
ii) Therefore [tex]\int k(x + 18)dx = \int kx + 18k dx[/tex] = [tex]k\frac{x^{2} }{2}[/tex] + [tex]18kx[/tex] + C where C is the constant of integration.
iii) the complete solution can only be found if we know the constant of proportion and also the constant of integration.
