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1. Hey all, I need urgent help for my maths homework

1) the mean braking distance, d yards, for a car is given in the formula d=(v^2/50)+(v/3), where v is the speed of the car in miles per hour.
a) sketch this graph for 0<v<80
b) estimate the safe braking distance for a car driving at i)15mph ii)45mph iii)75mph
c) A driver stops in time in a distance of 50 yards. How fast was the car travelling when teh brakes were applied?

and the second question is
2) use a suitable substitution to solve 2(k^6-11k^3)= 160 for k. Give your answers in exact form

any help really will be appreciated
2. Have you made a start? If so, please post what you've done so far and explain why you're stuck.
3. (Original post by _gcx)
Have you made a start? If so, please post what you've done so far and explain why you're stuck.
I haven't made a start because i have got no idea how to start it. I presume that the graph will be a U shape because it has an x^2. but after that i dont know how to go along with it
4. (Original post by cleverclogs15.)
I haven't made a start because i have got no idea how to start it. I presume that the graph will be a U shape because it has an x^2. but after that i dont know how to go along with it
Put it as one fraction, then consider the numerator which is a +ve quadratic, so yes it will have a U shape (or some portion of it, given the interval) - you can draw this? Then think of the denominator as the s.f. by which that graph is squished downward by - so its a transformation.
5. (Original post by cleverclogs15.)
I haven't made a start because i have got no idea how to start it. I presume that the graph will be a U shape because it has an x^2. but after that i dont know how to go along with it
Note: the question is asking you to sketch for , (think of what the curve is modelling) so it won't be a U-shape. A helpful observation is that the curve intersects the origin, as yields .
6. (Original post by cleverclogs15.)
Hey all, I need urgent help for my maths homework

1) the mean braking distance, d yards, for a car is given in the formula d=(v^2/50)+(v/3), where v is the speed of the car in miles per hour.
a) sketch this graph for 0<v<80
b) estimate the safe braking distance for a car driving at i)15mph ii)45mph iii)75mph
c) A driver stops in time in a distance of 50 yards. How fast was the car travelling when teh brakes were applied?

and the second question is
2) use a suitable substitution to solve 2(k^6-11k^3)= 160 for k. Give your answers in exact form

any help really will be appreciated
If you draw the axes of the graph sketch (you should know which way the axes go if you think about the equation in terms of Ys and Xs to make it easier/simpler), then you can plug values for v into the equation to get a corresponding value for d - this should help produce a graph sketch.

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