The cross section of a river, from one bank to the another, can be represented by the function d= 1/14 w^2 - 5/7 w; where 'd' is the depth in meters and "w" is meters from the river bank. How deep is the river at it's deepest point? Find the answer by using your graphing calculator, and state all steps taken to find the solution

Question

aum · Answer

Plot the function 1/14 w^2 - 5/7 w
This will be a vertical parabola that opens upward.
The vertex will be the lowest point and that is where the river is the deepest.
Find the y coordinate of the vertex and that would be the depth at the deepest point.

anonymous · Answer

oh so on the graphing calculator, i punch in 1/14 w^2 - 5/7 w?

anonymous · Answer

ek i have no idea what im doing ._.

aum · Answer

I don't have a graphing calculator myself but you will have to look up the manual to figure out how to graph functions.

aum · Answer

Or you can use an online graphing calculator such as https://www.desmos.com/calculator But change w to x because they expect a function of x.

anonymous · Answer

so then it becomes
 1/14 w^2 - 5/7 w
 1/14 x^2 - 5/7 x
 1/14 (0)^2 - 5/7 (0)

anonymous · Answer

and x = 0, since it's on the y coordinate?

anonymous · Answer

|dw:1404518935567:dw|

aum · Answer

No, just graph 1/14 x^2 - 5/7 x It will look like this: http://prntscr.com/3zhx10

aum · Answer

The lowest point is (5, -1.79)
The second coordinate is the depth and so the deepest depth is 1.79 meters.

anonymous · Answer

agh you're a life saver xD THANK YOU SO MUCH

aum · Answer

You are welcome.