x2 − 2xy + y2 + 2x + 2y = 0. factor
x'2 = 8y' – 2 y'2 = 4x x2 = 4y − 2 y'2 = 2x
What would the equation of the parabola be in terms of the rotated axes?
@e.mccormick
@dan815
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@sleepyjess
@KendrickLamar2014
I chopped the question up so people would come
@EclipsedStar
n engineer designing a roller coaster is using an advanced software application to test the strength of the structure. A part of the structure has a parabolic shape with the equation x2 − 2xy + y2 + 2x + 2y = 0. However, the software doesn't recognize any equation involving an xy term. What would the equation of the parabola be in terms of the rotated axes?
please wait I try
yea take your time
here, we have the subsequent matrix equation: \[\left( {\begin{array}{*{20}{c}} x \\ y \end{array}} \right) = \left( {\begin{array}{*{20}{c}} {1/\sqrt 2 }&{1/\sqrt 2 } \\ { - 1/\sqrt 2 }&{1/\sqrt 2 } \end{array}} \right)\left( {\begin{array}{*{20}{c}} {x'} \\ {y'} \end{array}} \right)\] where x' and y' are the new coordinates. Namely we have to compute the eigenvalues and the eigenvectors of the quadratic part of your parabola
so we can write: \[\begin{gathered} x = \frac{{x' + y'}}{{\sqrt 2 }} \hfill \\ y = \frac{{x' - y'}}{{\sqrt 2 }} \hfill \\ \end{gathered} \] those are the requested equation of our rotation
Now we have to substitute those equations into your parabola, in order to rewrite your parabola in term of x' and y',so what do you get?
substitute \[x=\frac{ x'+y }{ \sqrt{2} } and y=\frac{ x' -y'}{ \sqrt{2} }\] x2 − 2xy + y2 + 2x + 2y = 0
that?
yes!
how do you do that?
x = 1/4, y = -3/4
you wont me to substitute the factor in to the equation
the solution?
for example: \[\large \begin{gathered} {x^2} + {y^2} - 2xy + 2x + 2y = \hfill \\ \hfill \\ = {\left( {\frac{{x' + y'}}{{\sqrt 2 }}} \right)^2} + {\left( {\frac{{x' - y'}}{{\sqrt 2 }}} \right)^2} - 2\left( {\frac{{x' + y'}}{{\sqrt 2 }}} \right) \cdot \left( {\frac{{x' - y'}}{{\sqrt 2 }}} \right) + \hfill \\ + 2\frac{{x' + y'}}{{\sqrt 2 }} + 2\frac{{x' - y'}}{{\sqrt 2 }} = ...? \hfill \\ \end{gathered} \]
I got this: \[\Large y{'^2} + \sqrt 2 x' = 0\] please check my computations
y'^2 = 2x?
I think: y'2=-sqrt(2)x'
so its D
please can you check your options?
It is D:)
ok!
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