College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 2 - Section 2.4 - Circles - 2.4 Assess Your Understanding - Page 186: 25

Answer

(a) The circle has a center (3,0) and a radius of 2 units. (b) See below. (c) There are two x-intercepts: (1,0) and (5,0). There are no y-intercepts.

Work Step by Step

First, we need to make sure that the equation is in standard form $(x-h)^2+(y-k)^2=r^2$ In this case, we need to tidy the equation up a bit: $2(x-3)^2+2y^2=8$ $(2(x-3)^2+2y^2)/2=8/2$ $(x-3)^2+y^2=4$ $(x-3)^2+y^2=2^2$ Now we can find the center (h,k) and the radius. The x-intercepts are all points of a graph when y=0: $(x-3)^2+0^2=4$ $(x-3)^2=4$ $\sqrt{(x-3)^2}=\sqrt4$ There are two x-intercepts: $x_1-3=-2$ $x_1=1$ $x_2-3=2$ $x_2=5$ The y-intercepts are all points of a graph when x=0: $(0-3)^2+y^2=4$ $(-3)^2+y^2=4$ $9+y^2=4$ $y^2=-5$ $\sqrt{y^2}=\sqrt{-5}$ Taking the square root of a negative number isn't possible; therefore, this circle doesn't intersect the y-axis at any point.
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