Evaluate the line integral f · dr, c where c is given by the vector function r(t). F(x, y, z) = x i y j xy k, r(t) = cos(t) i sin(t) j t k, 0 ≤ t ≤ ������.

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hello from mrbilldoesmath!

answer:   x (x+6)^2, choice b

discussion:

factor x out of the equation:

x^3 + 12x^2 + 36x = x (x^2 + 12x + 36).

note that 6+6 = 12 and 6*6 = 36 so the above factors into:

x (x+6)^2

which is choice b

you,

mrb