Math Is Fun Forum

reallylongnickname

Member

Registered: 2011-03-30

Posts: 50

exponents and yx

I thought yx and exp were the same thing.
10 yx 1 = 10 on calculator but 10 exp 1 = 100

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: exponents and yx

Where did you get that 10 exp 1 is 100 from?

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reallylongnickname

Member

Registered: 2011-03-30

Posts: 50

Re: exponents and yx

The -3 is exponent.

If I go; 10 * 10^1 = 100
If I go; 10 exp 1 =100

Last edited by reallylongnickname (2012-06-16 13:03:34)

reallylongnickname

Member

Registered: 2011-03-30

Posts: 50

Re: exponents and yx

I keep making conversion errors. I can understand why it doesn't work on calculator if u go; 1 divide 10 times 10 yx -3
Why do you have to go; 1 divide 10 exp-3 to get the the answer in proper units.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: exponents and yx

hi reallylongnickname

On Texas Instruments calculators the

button computes the number <y> raised to the power <x>

On some other makes of calculator it is labelled

which is strictly incorrect but it doesn't matter too much unless you start swapping numbers between registers.

The button

is a short cut for

It is there to allow you to input numbers in standard form. Thus

The following shows why you get 100

There are two ways you can do the calculation you want:

or

You must include the brackets to force the power to the denominator and use the < +/-> swap signs button for the negative rather than the minus button.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

reallylongnickname

Member

Registered: 2011-03-30

Posts: 50

Re: exponents and yx

Thx, it is more clear now.

Here is a separate Q.
I want to type in this angular formula on calculator. How do I go about inputing "rad?"

Last edited by reallylongnickname (2012-06-17 13:37:15)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: exponents and yx

hi reallylongnickname

Scientific calculators can usually be changed to accept input in radians.  Is there a <mode> button?  Try that.  You may be able to change between degrees and radians with that.  As a test of whether you have done this successfully try sin(pi/2).

Another thing that would be worth trying once you have found out how to change angle mode is this:

Start in degrees and enter, say, 90.  Switch to radians.  What's in the display now?  Is it still 90? Or has it changed that too?

If you cannot find how to switch, post back what calculator you are using and I'll do some research.

Bob

picture shows a Canon calc.

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

reallylongnickname

Member

Registered: 2011-03-30

Posts: 50

Re: exponents and yx

I can put calc into rad mode, but still not sure how to compute the formula. What is to be inputted for "rad" in the formula?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: exponents and yx

hi reallylongnickname

I've looked again at your post.  It would help if I read posts properly before I answered; then I might give the right answer.  Sorry.  I've given myself a detention!

So, if I've understood properly this time, you want to convert angles from degrees into radians using that formula.

If so, then you don't need to input anything for the rads. 

Simpler example first:

Suppose you were changing inches into centimetres.  I inch is about 2.54 cm so you'd do this.

Input your measurement in inches, times by 2.54, display now shows the centimetres.

You wouldn't need to input anything for the cm would you?  In fact, your calculator wouldn't know what you were converting; it would just do the sum.

So for degrees to rads:

Input angle in degrees , times by 2, times by 'pi', divide by 360.  Display now shows the angle in radians.

You can save a few key presses by simplifying the formula.  Cancel a 2.  Formula becomes:

Input angle in degrees ,  times by 'pi', divide by 180.  Display now shows the angle in radians.

Have I answered your question now?

Test.  Change 45 degrees to radians.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob