How do you graph #f(x)=(2x^2-5x+2)/(2x^2-x-6)# using holes, vertical and horizontal asymptotes, x and y intercepts?

1 Answer
Jul 18, 2018

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Please read the explanation.

Explanation:

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The function:

#color(red)(f(x)=(2x^2-5x+2)/(2x^2-x-6)# Eqn.1 is rational.

#color(green)("Step 1:"#

Set #DR = 0#

#rArr 2x^2-x-6=0#

Factorize:

#rArr 2x^2+3x-4x-6=0#

#rArr x(2x+3)-2(2x+3)=0#

#rArr (2x+3)(x-2)=0#

Factors of #color(blue)(DR = (2x+3)(x-2)# Res.1

#color(green)("Step 2:"#

Set #NR = 0#

#rArr 2x^2-5x+2=0#

Factorize:

#rArr 2x^2-x-4x+2=0#

#rArr x(2x-1)-2(2x-1)=0#

#rArr (2x-1)(x-2)=0#

Hence, the factors of #color(blue)(NR = (2x-1)(x-2)# Res.2

#color(green)("Step 3:"#

Using the Res.1 and Res.2

Eqn.1 can now be rewritten as

#color(blue)(f(x)= [(2x-1)(x-2)]/[(2x+3)(x-2)]# Eqn.2

#color(blue)(f(x)= [(2x-1)cancel((x-2))]/[(2x+3) cancel((x-2)]#

#color(blue)(f(x)=(2x-1)/(2x+3)# Eqn.3

#color(green)("Step 4:"# Horizontal Asymptote

Refer to Eqn.1:

The leading coefficients of the highest terms are #color(red)(2, 2#

#rArr 2/2=1#

Horizontal Asymptote is at #color(blue)(y=1#

#color(green)("Step 5:"# Vertical Asymptote

Consider DR

#rArr 2x+3#

#rArr 2x=-3#

#rArr x=(-3/2)#

Vertical Asymptote is at #color(blue)(x=(-3/2)#

#color(green)("Step 6:"# Hole

Consider Eqn.2

#color(blue)(f(x)= [(2x-1)(x-2)]/[(2x+3)(x-2)]#

#color(blue)((x-2)# is the common factor,

Set #color(blue)((x-2)=0#

#color(blue)(x=2)#

y-coordinate value of the hole

#color(blue)(f(x)=(2x-1)/(2x+3)# Eqn.3

Substitute #color(red)(x=2#

#rArr (2*2 - 1)/(2*2+3#

#rArr 3/7#

Hence, the hole is at #color(blue)((2, 3/7)#

#color(green)("Step 7:"# x-intercept

Set #color(blue)(2x-1=0#

#rArr 2x=1#

#rArr x = 1/2#

Hence, the x-intercept is at #color(blue)((1/2, 0)#

#color(green)("Step 8:"# y-intercept

Consider: #y=(2x-1)/(2x+3)#

Substitute #color(red)(x=0#

#rArr (2*0-1)/(2*0+3)=-1/3#

y-intercept is at #color(red)((0, -1/3)#

#color(green)("Step 9:"# Graph

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