course Mth 163
When given the depth vs. clock time function f(t)=.021t^2+-2.34t+84 find clock time when depth = 68.8143 and when f(t)=39.814. I can do this problem when you asked to solve when t=some number. I dont understand how to do it if you are given f(t) and asked to find t.
When using the quadratic formula I always get a neg. under the sqrt.
To answer the first question you note that y = f(t) is the depth. So you substitute the given depth for f(t) to obtain the equation
68.8143 = .021t^2+-2.34t+84.
You solve this equation and obtain two values of t, about t = 7 and t = 105.
Remember that the quadratic formula applies only to the form a t^2 + b t + c = 0. If you don't have 0 on one side, you have to rearrange the equation so you do.
Be sure you have memorized the entire statement of the quadratic formula as prominetly indicated in your worksheets.
If you have further difficulties with this, submit a complete detailed attempt at solution so I can see where you are going wrong. The above is based on my best guess, but a detailed solution would make it clear where you are going wrong here.