# Homework Help: Calculator (root) problem (Exam tomorrow) HP 10s assistance

1. Jan 18, 2016

### MrAAK

1. The problem statement, all variables and given/known data
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!!

2. Relevant equations

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

3. The attempt at a solution

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.

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• ###### parenthesis raised to a division.png
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2. Jan 18, 2016

### 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".

3. Jan 18, 2016

### MrAAK

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.

4. Jan 18, 2016

### 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?

5. Jan 18, 2016

### MrAAK

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...

6. Jan 18, 2016

### Staff: Mentor

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

7. Jan 18, 2016

### 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 $\sqrt(....)$

8. Jan 18, 2016

### MrAAK

Yeah, I know, for complex numbers etc, but this is just a simple bedmas operation under the radical.
It wont accept more than the first digit under the radical. (so if its a negative X negative etc, its no use).

9. Jan 18, 2016

### MrAAK

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

10. Jan 18, 2016

### MrAAK

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 shouldnt have done that), oh well...exam stress etc.
Thanks guys!

11. Jan 19, 2016

### MrAAK

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

12. Jan 21, 2016

### 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!