Mathematics
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OpenStudy (howard-wolowitz):
ONE QUESTION! @=people
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OpenStudy (howard-wolowitz):
@Michele_Laino
OpenStudy (michele_laino):
here we have to conjecture a linear relationship between y and x, namely:
y=a*x+b
x= elongation
y= applied mass
OpenStudy (michele_laino):
using your data, we can write:
\[\left\{ \begin{gathered}
70 = a \times 18 + b \hfill \\
100 = a \times 24 + b \hfill \\
\end{gathered} \right.\]
OpenStudy (michele_laino):
we have to solve that system for "a" and "b"
OpenStudy (howard-wolowitz):
alright, solving for a and b
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OpenStudy (michele_laino):
yes!
OpenStudy (michele_laino):
for example I solve the first equation for b, and I get:
\[b = 70 - 18a\]
OpenStudy (michele_laino):
then I substitute that expression into the second equation, so I can write:
\[100 = 24a + \left( {70 - 18a} \right)\]
OpenStudy (michele_laino):
what is a?
OpenStudy (howard-wolowitz):
actualy no
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OpenStudy (michele_laino):
we have to simplify as below:
\[100 = 24a + 70 - 18a\]
OpenStudy (howard-wolowitz):
ok one sec
OpenStudy (howard-wolowitz):
5
OpenStudy (michele_laino):
\[\begin{gathered}
100 = 70 + 6a \\
100 - 70 = 6a \\
\end{gathered} \]
OpenStudy (howard-wolowitz):
ok one sec
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OpenStudy (michele_laino):
ok! a= 5
OpenStudy (howard-wolowitz):
a=5 for both
OpenStudy (michele_laino):
now I substitute a=5 into the first equation, for example, so I get:
\[\begin{gathered}
70 = 18 \times 5 + b \\
70 = 90 + b \\
\end{gathered} \]
OpenStudy (michele_laino):
what is b?
OpenStudy (howard-wolowitz):
-20
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OpenStudy (michele_laino):
ok! so our relationship is:
y=5x-20
OpenStudy (howard-wolowitz):
you mean 1/5x
OpenStudy (howard-wolowitz):
ohh I see nvm sorry
OpenStudy (michele_laino):
no, y= 5x-20
I have made an error, when I wrote:
x= elongation y= applied mass
OpenStudy (michele_laino):
nevertheless to get the right answer it is suffice to change x, y each other
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OpenStudy (michele_laino):
so we can write:
x=5y-20
OpenStudy (michele_laino):
then we can solve that equality for y, and we get this result:
\[y = \frac{1}{5}x + 4\]
OpenStudy (michele_laino):
since your problem consider x as the applied weight
and y the elongation produced by that weight
OpenStudy (michele_laino):
as you can see I have conjectured viceversa
OpenStudy (howard-wolowitz):
yes I get it
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OpenStudy (michele_laino):
so, what is the right option?
OpenStudy (howard-wolowitz):
D?
OpenStudy (michele_laino):
yes!