Algebra II Honors`

1. Dec 9, 2011

darshanpatel

I don't get the wording of the problem. What does it mean find the equation?

Problem: Find the equation of the secant line through the points (x, f(x)) and (x2, f(x2)) for parts (a)-(e) in Exercise 5.

There is no work because I don't know where to begin.

Just as an example, (a) in Exercise 5 is x=2 and x2=3...
What do I do?

They also give me m(sec)= f(x2)-f(x)/x2-x

2. Dec 9, 2011

SammyS

Staff Emeritus
The equation of a line is often of the form
y = mx + b

for instance, y = 3x - 7​

3. Dec 9, 2011

darshanpatel

I know it is y=mx+b but how would i find that? Can you please show using the example numbers?

4. Dec 9, 2011

SammyS

Staff Emeritus
Were you given a specific function for this problem?

5. Dec 9, 2011

darshanpatel

Yes for exercise 5 it said consider the function given by f(x)=sqrt(x-1)

6. Dec 9, 2011

SammyS

Staff Emeritus
What are f(2) and f(3) ?

7. Dec 9, 2011

darshanpatel

what do you mean?

8. Dec 9, 2011

SammyS

Staff Emeritus
You are given the function $f(x)=\sqrt{x-1}\,.$

So I asked, "What are f(2) and f(3) ?" . That's a very basic question.

9. Dec 9, 2011

darshanpatel

oh, f(2)=1 and f(3)=sqrt2

10. Dec 9, 2011

darshanpatel

I tried putting it into point-slope form and got y-1=(sqrt2-1)(x-2), is that a right start?

Reduced that down to y=(sqrt2x -x)-2sqrt2 +3

Last edited: Dec 9, 2011
11. Dec 9, 2011

darshanpatel

SammyS u still want to help me?

12. Dec 9, 2011

Staff: Mentor

Yes
Right, though it is usually better to write it with just one x,
viz., y = (sqrt2 - 1)x -2sqrt2 + 3

But you are not finished yet. The final step is to check that this equation fits your initial data, to avoid the embarrassment of scoring some red crosses when your work is marked.

When x=2, does this produce a y value of 1?
when x=3, does this give y = sqrt2?

If this all tallies, then it must be right.

13. Dec 9, 2011

Staff: Mentor

This -- sqrt2x -- is terrible notation because it is ambiguous. Does it mean $\sqrt{2x}$ or does it mean $\sqrt{2}\cdot x$? Because this expression came from (=(√2-1)(x-2), you apparently intend for what you wrote to mean $\sqrt{2}\cdot x$. A better way to write that is to put x in front of the radical, as x√2, which is clear and unambiguous.

14. Dec 10, 2011

darshanpatel

Thank you, sorry, i see it written a lot like sqrt2 or what ever, but how do you do the symbols?

15. Dec 11, 2011

Staff: Mentor

To use the typesetting fonts and symbols, you have to invest time in learning Latex-family formatting. This site makes it as effortless as possible: http://www.codecogs.com/latex/eqneditor.php

You can construct your itex formatting on that site, then cut and paste it into your posts.