Question

Evaluate the algebraic expression for the given value(s) of the variable(s).
x^2-10x+5/x^2+2x-1;x=4

Answer 1

Replace all the x's in your function with a 4.

Answer 2

By any chance do you have a TI-83 or TI-83Plus calculator?

Answer 3

Yes I do.

Answer 4

Want to know a really easy way to solve these for various numbers?

Answer 5

You have to have your calculator ready and follow all my step-by-steps, if you want to know, ok?

Answer 6

Yes Please.

Answer 7

ok, ready?

Answer 8

clear your screen. Then hit "4", then "STO", then the X,T,theta,n key which is just under your Mode key. Got that?

Answer 9

You should see this: 4->X

Answer 10

Then hit enter.

Answer 11

You stored 4 as your first x value for your polyomial by doing this.

Answer 12

Now enter your polynomial, using the X,T,theta,n key as your x variable and the ^ key for the powers on the x's.

Answer 13

You will still have the 4 on the screen, just start your polynomial on the next line.

Answer 14

Enclose each polynomial in parenthesis...the one on the top then the one on the bottom.

Answer 15

Ok I have -19/23. is this correct???

Answer 16

Did you enclose the numerator in parenthesis and then hit the divide button and then enclose the denominator in parenthesis and then hit enter?

Answer 17

your screen should look like this:

Answer 18

4->X
4
(x^2-10x+5)/(x^2+2x-1)

Answer 19

When you hit enter you get a value of -.82608 when x = 4. Try that again and then I will show you the beauty of knowing this trick.

Answer 20

And yes, actually you were right on that -19/23. Now, say we want to find another value of x, and this time we want x = 6.

Answer 21

Leave the stuff on the screen and then hit 6, then "STO", then x, then enter.

Answer 22

Then hit the 2nd button, the enter button, the 2nd button again, the enter button again, and then the enter button again.

Answer 23

what does that give you?

Answer 24

I have 0.40425.

Answer 25

I meant -0.40425

Answer 26

yes that's it! When you know how to do that on your calculator, you only have to type in the function once, and then you can keep checking all different values of x by just hitting the 2nd and the enter in the order I told you. It's really cool when you start working with polynomials and rational roots and the remainder theorem and stuff like that! Keep it in mind!

Answer 27

Thank you for all the help!!! I really appreciate it!!!

Answer 28

Now you have your value of x = 4. Right? If there are any more like that, use that calculator and let it help you!

Answer 29

You're welcome! It's a tip I taught my Algebra 2 students and it is indispensable!