How do you graph f(x)=(x^2+3x)/(x^2-x)f(x)=x2+3xx2−x using holes, vertical and horizontal asymptotes, x and y intercepts?
1 Answer
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]}