# 2 Calculus questions

1. Dec 14, 2004

### vee123

I have two Calculus problems I need explained because I'm studying for a final exam and I forgot how to do these things:

#1: Find the point that lies on the line determined by the points (1,-2) and (-3,1).

The answer is (5,-5), but I don't know why....

#2: Write an equation satisfied by the graph obtained by shifting y=2x-5 three units to the left.

I know when an equation is shown moving to the left, it is put in parentheses and a number is added to it (for example y=x^2 becomes y=(x^2+2) when it is moved two places to the left). However, I do not know how to do this problem.

2. Dec 14, 2004

### cyby

Several things you can do. First off, these aren't calc questions, afaik.

1. Can you write down the equation determined by the two points? If so, then I guess you have choices to plug into the equation to see if they work.

2. The easiest thing to do is to just plot the thing and move it 3 units to the left, and see what you get. But you can also just apply some transforms. In your case, you can shift your function to the left ( f(x) -> f(x+3) ) by applying that transform.

See what you get :)

3. Dec 14, 2004

### vee123

Thanks for the reply! I think I'm starting to remember this...

Yeah I know these aren't really calc questions, but they were in the begining section of my calc. book.

4. Dec 14, 2004

### cyby

Anytime :D

5. Dec 14, 2004

### vee123

Okay, I'm still having trouble with the second question. I know I may sound really stupid, but I tried to solve it by doing f(x)=(2x-5+3), and did not get the correct answer. What am I doing incorrectly?

6. Dec 14, 2004

### cyby

Consider rewriting f(x) = 2x-5 as f(x) = 2(x-5/2).. and see if you get anything from there...

7. Dec 14, 2004

### vee123

Now I understand! I was having a bit of a mental block at hte moment... Thank you very much! :)