ElectricPavlov

Another option is to graph (plot) the x =2t^2-16t+35    and you will se that the graph never reaches zero..(i.e. the car never reaches the tree)....the low point (nadir) is at t=4 with a value of 3 (as found in the previous solution)..

SInce you need to use the quadratic formula    ( -b +- sqrt(b^2-4ac))  / 2a

For the first one a =1 b=-3 c=-10         (3 +- sqrt(9- (-40)  )/2(1)  = ( 3 +- sqrt49 )/2    = (3+-7) / 2 = x =  5 or -2

You can now do the other one!

(7x-7y) ^2 =

49x^2  -49xy -49xy +49y^2 =

49x^2 - 98xy +49y^2

You COULD subtract   like this     3/4 - 3/4(1/5)

or you could just multiply.   If you USE 1/5 of the gas, then 4/5 is left    3/4  x 4/5 = 12/20 = 3/5 tank left

840sale  -(6.22 cost ) x 35 = 622.30 TOTAL PROFIT       or        17.78 profit on EACH PAIR    

If we take dx/dt of the x= distance equation we will get the velocity = 4t-16       When the car comes to a stop, the velocity = 0 , so setting this equation = 0 will give us t in seconds when the car stops:

4t-16 = 0     yields car stop at t= 4 seconds    NOW, going back to the DISTANCE BETWEEN equation with t= 4

x= 2t^2 - 16t +35    yields     32 -64 +35 = 3 meters between the car and the tree...so the car will NOT hit the tree, but stop 3 meters from it.

The distance the car travels is the difference between t= 0 and t= 4 for the distance between equation given

t=0  yields  35     t= 4 we found = 3     35-3 = 32 meters = distance car travelled

Hmmmm.... works for me.    Watch ABOVE the calculator to see if it is interpreting your input the way you intended....

Look up law of cosines and law of sines

Let's express auto parts in terms of man-hours 

12 man x 7 days x 9hrs/day / 390 parts = 1.93846 man-hr / part

Now   a)    21 days x 8 hrs/day x ?men /  2340parts = 1.93846 man-hr/part  ???

                168 x ? / 2340 = 1.93846

                   ? =    1.93846 x (2340)/168 = 26.99  = ~ 27 EMPLOYEES

          b)    20 men x 18 days x 7.5 hours / ? parts  = 1.93846 man-hr / part

                                          20 x 18 x 7.5 /1.93846 = ? parts =  1392.85  =  ~ 1393 parts