Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 11 - Section 11.6 - Further Graphing of Quadratic Functions - Practice - Page 814: 2

Answer

no x-intercepts y-intercept is $(0,5)$ vertex is $(-1/2,9/2)$

Work Step by Step

$f(x)=2x^2+2x+5$ $y=2x^2+2x+5$ $y-5=2x^2+2x$ $(y-5)/2=(2x^2+2x)/2$ $y/2-5/2=x^2+x$ $y/2-5/2+(1/2)^2=x^2+x+(1/2)^2$ $y/2-5/2+1/4=x^2+x+1/4$ $y/2-9/4=(x+1/2)^2$ $y/2-9/4=(x+1/2)^2$ $0/2-9/4=(x+1/2)^2$ $-9/4=(x+1/2)^2$ Since we would be taking the square root of a negative number, we know that there are no x-intercepts. y-intercept: $f(x)=2x^2+2x+5$ $f(0)=2*0^2+2*0+5$ $f(0)=0+0+5$ $f(0)=5$ Vertex: $y=2x^2+2x+5$ $y-5=2x^2+2x$ $(y-5)/2=(2x^2+2x)/2$ $y/2-5/2=x^2+x$ $y/2-5/2+(1/2)^2=x^2+x+(1/2)^2$ $y/2-5/2+1/4=x^2+x+1/4$ $y/2-9/4=(x+1/2)^2$ $2*(y/2-9/4=(x+1/2)^2)$ $y-9/2=2(x+1/2)^2$ Vertex of $(-1/2,9/2)$
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