He has biked 2.85 miles. By multiplying 28.5 and 0.10 or dividing 28.5 by 10 you get the total 2.85. To check your answer you can multiply 2.85 by 10 which equals 28.5. Hope this helps!
R(t) = integral of r'(t) = integral of ti + e^tj + te^tk = 1/2t^2i + e^tj + (te^t - e^t)k + c
r(0) = j - k + c = i + j + k
c = i + 2k
Therefore, r(t) = (1/2t^2 + 1)i + e^tj + (te^t - e^t + 2)k
Sur it's a function because for each x value corresponds one and only one y value.
Another easy way to determine if y is a function is to apply the vertical test:
If you draw a vertical line and this lines intersects the graph in one point, then y is a function
