Math help[NA]

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Display name:
Dave Taylor
Known plots:
X=966 Y=8.54
X=1299 Y=7.87
I need an equation where I enter X each time to figure Y
Tks
Too many decades since I did this
Real world need, not hypothetical
 
Assuming a linear fit, 2 points only:

slope m = (y1 - y2)/(x1 - x2)

m = (8.54 - 7.87)/(966 - 1299) = -2.01e-3

y = mx + b => b = y - mx

choose any point:

b = 8.54 - (-2.01e-3 * 966) = 10.5

so y = -2.01e-3 x + 10.5

I've kept each of the calculated values to 3 sigdigs.
 
Last edited:
Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “
 

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Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “

-0.00201

And I should have written:

y = -2.01e-3x + 10.5

I forgot the x when I orignally posted. It's corrected now


Sent from my iPhone using Tapatalk Pro
 
Rotate your phone 90 deg. ;)

Nauga,
and his direction cosine matrix

Or download pcalc. RPN!

acacbb5fd6d491c4397e4d180c7a8f23.png
 
I learned in college -- if you expect the results to be a straight line, only plot 2 points.


I learned it as, “Two points define a line and three points don’t. Three points define a plane and four points don’t.”
 
I learned it as, “Two points define a line and three points don’t. Three points define a plane and four points don’t.”
One point defines a line if the line is going directly away from you.
 
Let's get this straight...don't want any pointless discussion, y'all hear?
 
Folks, I think we’re done here. End of the line.
 

Kids and their "software this and software that". :rolleyes:


pahZqdl.jpg


Bought my HP-15C shortly after college graduation. It carried me through 36 years of engineering practice at Lockheed and it’s still going strong now that I’m doing pro bono stuff.

They don’t build ‘em like that anymore and that’s a real shame.
 
Bought my HP-15C shortly after college graduation. It carried me through 36 years of engineering practice at Lockheed and it’s still going strong now that I’m doing pro bono stuff.

They don’t build ‘em like that anymore and that’s a real shame.

Bought this one in 1984 after my original 43C died. Still use it almost every day.
 
Photomath is the real answer to sleeping through math class. Point. Shoot. Solved.
upload_2021-11-30_16-9-25.png
 
Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “

OP, e-3 means "times 10 to the -3 power", i.e. move the decimal point three places left. It became common with computers, which don't handle superscripts. IIRC, I first encountered this when using Lotus 1-2-3 in the 1980s. Here is a Wiki page which addresses this; look about 1/3 the way down:

https://en.wikipedia.org/wiki/Scientific_notation
 
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