- #1
Bitter
- 98
- 0
Here is the problem I am having trouble with right now.
The number of miles M that a certain compact car can travel on 1 gallon of gasoline is related to its speed v (in mi/hr) by
M=-1/30v^2+5/2v for 0<v<70
For what sppeds will M be at least 45?
I start working the problem like this:
45=-1/30v^2 +5/2v
I then put the problem into a polynomial
-1/30v^2 + 5/2v -45
I'm fairly certain you can factor that but if not I use the quadratic.
-5/2 +- Sqr of .25 all over -1/15
That comes out to be 75/2 plus or .5
Which is equal to 38 and 37
Now three things are possible. a) I am heading in the wrong direction or b)I did something wrong or c)all the above
The number of miles M that a certain compact car can travel on 1 gallon of gasoline is related to its speed v (in mi/hr) by
M=-1/30v^2+5/2v for 0<v<70
For what sppeds will M be at least 45?
I start working the problem like this:
45=-1/30v^2 +5/2v
I then put the problem into a polynomial
-1/30v^2 + 5/2v -45
I'm fairly certain you can factor that but if not I use the quadratic.
-5/2 +- Sqr of .25 all over -1/15
That comes out to be 75/2 plus or .5
Which is equal to 38 and 37
Now three things are possible. a) I am heading in the wrong direction or b)I did something wrong or c)all the above