Friday, October 14, 2016

College Algebra, Chapter 8, Review Exercises, Section Review Exercises, Problem 36

Identify the type of curve which is represented by the equation 3x2(6x+y)=10
Find the foci and vertices(if any), and sketch the graph

3x2(6x+y)=10Distribute 63x26x6y=10Add 6y3x26x=10+6yFactor 3 from the right3(x22x)=10+6yDivide by 3 both sidesx22x=103+2yComplete the square; Add (22)2=1x22x+1=103+2y+1Perfect Square(x1)2=2y+133Factor out 2 from the right(x1)2=2(y+136)

The equation is parabola that has form (xh)2=4p(yk) with center at (h,k) and opens upward. The graph is obtained from x2=4py by shifting 1 unit
to the right and 136 units downward. And since 4p=2, we have p=12. It means that the focus is
12 units above the vertex. Therefore, the following is determined as

vertex (1,136)foci (1,136+12)(1,53)

Then, the graph is

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