The velocity of a particle moving in the xy plane is given by = (5.6 t - 4.5 t2) + 8.2, with in meters per second and t (> 0) in seconds. (a) What is the acceleration when t = 3.3 s? (b) When (if ever) is the acceleration zero? (c) When (if ever) does the speed equal 10 m/s?(adsbygoogle = window.adsbygoogle || []).push({});

I got the first 2 but when I went to find c I can't seem to get it.

I took

10m/s = sqrt((5.6t - 4.5t^2)^2 + (8.2)^2

10^2 = (sqrt((5.6t - 4.5t^2)^2 + (8.2)^2)^2

100 = (5.6t - 4.5t^2)^2 + 67.24)

32.76 = (5.6t - 4.5t^2)^2

sqrt(32.76) = sqrt((5.6t - 4.5t^2)^2)

5.72 = 5.6t - 4.5t^2

0 = -4.5t^2 + 5.6t - 5.72

then I used quadratic to find out the two values...

but I get a negative in the sqrt on the quadratic and I can't do that... any suggestions?

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# Homework Help: Problem with vectors

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