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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: yanna.banana on June 27, 2016, 04:23:22 PM

Title: quadratic formula
Post by: yanna.banana on June 27, 2016, 04:23:22 PM
can someone give me a step by step walk through of this

here is my equation 0=x^​2​​ +6.3*10^​−8x−1.0*10^−14
 the answers are 7.3*10^-8 and -1.4*10^-7
i keep obtaining
6.3*10^-8 +/- 2.01*10-7 divided by 2 giving me
2.64*10^-7 and -1.38*10^-7
​​
Title: Re: quadratic formula
Post by: Borek on June 27, 2016, 05:50:59 PM
6.3*10^-8 +/- 2.01*10-7 divided by 2 giving me
2.64*10^-7 and -1.38*10^-7​

No way to reproduce these numbers. I suspect you are misusing your calculator.

Note: the correct formula calls for -b, not b (so (-6.3×10-8±2.10×10-7)/2).
Title: Re: quadratic formula
Post by: yanna.banana on July 01, 2016, 11:27:44 AM
okay then it must be a copying error my issue is i never am able to solve this quadratic properly.
i have  right now (for a different question)
0= x^2-1.74*10^-6 + 10^-4.76x

i am obtaining  +4.17*10^-3 and - 4.17*10^-3 and it is not correct.
Can someone show me a step by step?
thanks it would be so helpful.. i think the scientific notation is throwing me off. as i can solve with regular numbers
Title: Re: quadratic formula
Post by: mjc123 on July 01, 2016, 11:36:30 AM
Why don't you show us step by step how you got those numbers? We could go through it for you, but if your problem is that you are entering it into a calculator incorrectly, that won't help you.

PS Did you use 1.74 x 10-5 instead of 1.75 x 10-6?