Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 11 - Section 11.4 - Shifted Conics - 11.4 Exercises - Page 815: 51

Answer

$\frac{(x-3)^2}{25}+\frac{(y+5)^2}{4}=1$ Ellipse: center $C(3, -5)$, foci $F(3\pm\sqrt {21}, -5)$, vertices $V_1(-2,-5)$ and $V_2(8,-5)$ lengths of the major axis $10$, length of the minor axis $4$ See graph.

Work Step by Step

Step 1. Form squares with the variables: $4(x^2-6x+9)+25(y^2+10y+25)=36+625-561$ or $4(x-3)^2+25(y+5)^2=100$. Divide both sides by 100, we get $\frac{(x-3)^2}{25}+\frac{(y+5)^2}{4}=1$ Step 2. We can identify the above equation as an ellipse with a center at $C(3, -5)$ Step 3. With $a=5, b=2$, we have $c=\sqrt {25-4}=\sqrt {21}$ Step 4. We can find the foci at $F(3\pm\sqrt {21}, -5)$ Step 5. The vertices are $(3\pm5, -5)$ or $V_1(-2,-5)$ and $V_2(8,-5)$ Step 6. The lengths of the major axis is $2a=10$ and the length of the minor axis is $2b=4$ Step 7. See graph.
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