• Apr 1st 2012, 06:18 AM
davellew69
Hi all can you help, I have been asked to give answer in decimal to a quadratic formula. I have attached my workings, but Im not sure if my answers are correct, If I have made and error, can I get a pointer as to what I have done wrong...Many thanks.

Attachment 23489
• Apr 1st 2012, 06:24 AM
Vinceee
(11 + root97) / 2 = 10.4244289

(11 - root97) / 2 = 0.5755710991
• Apr 1st 2012, 06:47 AM
davellew69
thanks for the reply, I have just done it all again and the scientific calculator is giving me my origional answer,but a standard calculator give me your answers? lost
Dave
• Apr 1st 2012, 07:10 AM
Wilmer
Quote:

Originally Posted by davellew69
thanks for the reply, I have just done it all again and the scientific calculator is giving me my origional answer,.....

Well, you're not "feeding it" properly then: the FULL [-b +- SQRT(b^2 - 4ac)] has to be divided by (2ac);
you're going: -b +-[SQRT(b^2 - 4ac)]/(2ac) ; OK?
• Apr 1st 2012, 07:14 AM
davellew69
same answer as I get the first time
• Apr 1st 2012, 07:16 AM
Vinceee
@wilma
http://screensnapr.com/e/2mE0dZ.jpg

just 2a

@OP degrees mode calculator?
• Apr 1st 2012, 07:18 AM
Vinceee
I see what you've done wrong here...

You've put 11+ on its own so you're doing 11 +- (root97 / 2)

What you want to do is (11+- root97) / 2
• Apr 1st 2012, 07:22 AM
davellew69
you have lost me vince
• Apr 1st 2012, 07:26 AM
Vinceee
What you did:
http://screensnapr.com/e/J0Sbkt.jpg

What you should have done:
http://screensnapr.com/e/45RUnY.jpg

The 11+ or - goes within the divide by 2 part, which you put outside of it.
• Apr 1st 2012, 07:27 AM
davellew69
why do i do it that way?
• Apr 1st 2012, 07:37 AM
davellew69
lol got it...now I see why the brackets are used that way on a scientific calculator, thanks so much for your help..top fella, many thanks

Dave
( I may get got at this one day lol)
• Apr 1st 2012, 07:37 AM
Vinceee
If you have a scientific calculator:

fraction button -> 11 +- square root 97 -> down button -> 2

Natural display calculators mean you don't need the brackets on the calculator.

If you need more help just PM me here and it'll give me an email.
• Apr 1st 2012, 07:41 AM
Wilmer