How do you graph f(x)=(x^2+3x)/(x^2-x)f(x)=x2+3xx2x using holes, vertical and horizontal asymptotes, x and y intercepts?

1 Answer
Jan 3, 2018

"see explanation"see explanation

Explanation:

"factorise the numerator/denominator"factorise the numerator/denominator

f(x)=(cancel(x)(x+3))/(cancel(x)(x-1))=(x+3)/(x-1)

"the cancelling of the factor x indicates a hole at x = 0"

"substitute x = 0 into "f(x)=(x+3)/(x-1)

rArrf(0)=3/(-1)=-3

rArr"there is a hole at "(0,-3)

"the graph of "(x+3)/(x-1)" is the same as the graph of"

(x^2+3x)/(x^2-x)" but without the hole"

The denominator of f(x) cannot be zero as this would make f(x) undefined. Equating the denominator to zero and solving gives the value that x cannot be and if the numerator is non-zero for this value then it is a vertical asymptote.

"solve "x-1=0rArrx=1" is the asymptote"

"horizontal asymptotes occur as"

lim_(xto+-oo),f(x)toc" (a constant)"

"divide terms on numerator/denominator by x"

f(x)=(x/x+3/x)/(x/x-1/x)=(1+3/x)/(1-1/x)

"as "xto+-oo,f(x)to(1+0)/(1-0)

rArry=1" is the asymptote"

color(blue)"for intercepts"

• " let x = 0 for y-intercept"

• " let y = 0 for x-intercepts"

f(0)=-3larrcolor(red)"y-intercept"

y=0tox+3=0rArrx=-3larrcolor(red)"x-intercept"
graph{(x+3)/(x-1) [-10, 10, -5, 5]}