# Thread: How do you solve these without DE?

1. ## How do you solve these without DE?

I'm looking at my friend's grade 12 calculus assignment and I don't get some of the questions in it.

http://distance.kpdsb.on.ca/MCB4UAssignment6a.pdf

Questions 6, 7, and 8 look like differential equation questions. Obviously DE is not taught in grade 12, how would you solve them without knowledge in DE?

2. Originally Posted by chengbin
I'm looking at my friend's grade 12 calculus assignment and I don't get some of the questions in it.

http://distance.kpdsb.on.ca/MCB4UAssignment6a.pdf

Questions 6, 7, and 8 look like differential equation questions. Obviously DE is not taught in grade 12, how would you solve them without knowledge in DE?
Direct integration and Separation of variables is usually taught in high school calculus (I know that's the case in the US but I'm not sure what its like for other countries). As a result, they "should" know how to solve cooling problems using separation of variables along with given initial conditions.

If you can't use separation of variables, then you'll have to assume that the equation for temperature is $\displaystyle T(t)=S+T_0e^{-kt}$, where $\displaystyle T_0$ is the initial temperature and $\displaystyle S$ is the surrounding temperature.

3. Originally Posted by Chris L T521
Direct integration and Separation of variables is usually taught in high school calculus (I know that's the case in the US but I'm not sure what its like for other countries). As a result, they "should" know how to solve cooling problems using separation of variables along with given initial conditions.

If you can't use separation of variables, then you'll have to assume that the equation for temperature is $\displaystyle T(t)=S+T_0e^{-kt}$, where $\displaystyle T_0$ is the initial temperature and $\displaystyle S$ is the surrounding temperature.
Oh right! I forgot you can assume an equation like that. I wonder how they explain this general equation to the students (when you go to university you'll know?)

In Canada, grade 12 calculus is only differential. The first term of first year university is still differential (wrapping it up with topics like L'Hopital rule and mean value theorem)