Calculator (root) problem (Exam tomorrow) HP 10s assistance

[MrAAK]

Homework Statement

Hello, I have to use the HP 10s calculator at my university, I have been used to my modern casio for the last 4 years but I have a problem.
The square root symbol when pressed does not allow for continual calculation, such as when I am using the quadratic formula.
It seems to only take the square root of the first in-putted integer then does not continue the radical.
(Such as like on any Casio fx, you would press the right cursor to get out of the root and end your radicand).
On this thing, it just takes the root of the first number!
How do I keep the radical going for continual calculation??
Exam tomorrow, panic mode has started!

Homework Equations

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For this example, I was trying to use b^2-4ac under the radical, where a=1, b=4, c=-21

The Attempt at a Solution

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I have attempted nested parenthesis, parenthesis raised to the power of 1/2.
I have included two images that might show you what I mean.
Thanks for your help in advance.

 

[QuantumQuest]

You can always go from inside to outside. So, for instance you can form the expression for the discriminator and then take the square root. For more info take a look in the manual of hp 10s http://h10032.www1.hp.com/ctg/Manual/c01768863.pdf at "Continuous calculation".

 

[MrAAK]

You can always go from inside to outside. So, for instance you can form the expression for the discriminator and then take the square root. For more info take a look in the manual of hp 10s http://h10032.www1.hp.com/ctg/Manual/c01768863.pdf at "Continuous calculation".

Hi Quantum, thanks for your reply, I have the manual here with me, I tried that.
I pressed root 4^2= ANS popped up then I tried the rest.
Math error.
Can't square negative numbers.

 

[QuantumQuest]

According to the first image you've provided, you're trying to find a discriminator. Why not taking 4² - 4*1*(-21) and then take the square root?

 

[MrAAK]

According to the first image you've provided, you're trying to find a discriminator. Why not taking 4² - 4*1*(-21) and then take the square root?

Mainly for reasons of long winded decimal points, I would have to use just 3 decimals in order to maintain my time frame.
(Also accuracy).
It's easy with 100 under the radical, for an answer I should be getting of 10. But when I am in the exam, its going to be 4.798687692 etc...

 

[Mark44]

Can't square negative numbers.

Sure you can, but you can't take the square root of a negative number.

 

[TSny]

If you are going to take the square root by raising to the 1/2 power, try putting the power of 1/2 in parentheses: (...)^(1$\div$2)

To use the √ key: After √ put the entire expression that you want to take the square root of in parentheses $\sqrt(...)$

 

[MrAAK]

Sure you can, but you can't take the square root of a negative number.

Yeah, I know, for complex numbers etc, but this is just a simple bedmas operation under the radical.
It won't accept more than the first digit under the radical. (so if its a negative X negative etc, its no use).

 

[MrAAK]

If you are going to take the square root by raising to the 1/2 power, try putting the power of 1/2 in parentheses: (...)^(1$\div$2)

To use the √ key: After √ put the entire expression that you want to take the square root of in parentheses $\sqrt(...)$

Thats an idea, ill give that a go, two secs.

 

[MrAAK]

If you are going to take the square root by raising to the 1/2 power, try putting the power of 1/2 in parentheses: (...)^(1$\div$2)

To use the √ key: After √ put the entire expression that you want to take the square root of in parentheses $\sqrt(...)$

You sir, have saved me a sleepless night. I'm smoking this one for you(The manual)! I have been panicking for about 3 hours, I tried nested before and it didnt work? Bizarre!
Thanks! (I emailed my Professor at 11pm, probably shouldn't have done that), oh well...exam stress etc.
Thanks guys!

 

[MrAAK]

Sure you can, but you can't take the square root of a negative number.

Yeah, sorry, that's what I meant to say.

 

[MrAAK]

I think I 70%'d the maths and today, if I left that physics exam with less than 90%, I would not be amused.
Well, as long as its above 70% I am happy. Thank you al for your help. It was invaluable!