Evaluate the following line integral

178 Views Asked by At

$\int_c z^2dx+x^2dy+y^2dz$

C is the line segment from (1,0,0) to (3,1,4)

My work:

$\int_c z^2dx+x^2dy+y^2dz$

x = 1 + 3t, dx = 3dt

y = t, dy = 1dt

z = 4t, dz = 4dt

I replaced the original x,y,z and dx,dy,dz

= $\int_0^1 (4t)^2*3dt+(1+3t)^2*1dt+(t)^2*4$dt

= $\int_0^1 48t^2dt+1+6t+9t^2dt+4t^2$dt

= $\int_0^1 61t^2+6t+1dt$

= $ \frac{61t^3}{3}+3t^2+t |_0^1$

= $ \frac{61}{3}+3+1 - (0)$

= $ \frac{61}{3}+4$

= $ \frac{61}{3}+\frac{12}{3}$

= $ \frac{73}{3}$

However this answer is wrong, and i'm not sure why.