What is the domain and range for f(x) = - ( 1 / ( x + 1) )f(x)=−(1x+1)?
1 Answer
May 25, 2018
Explanation:
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.
"solve "x+1=0rArrx=-1larrcolor(red)"excluded value"solve x+1=0⇒x=−1←excluded value
"domain "x in(-oo,-1)uu(-1,oo)domain x∈(−∞,−1)∪(−1,∞)
"for the range rearrange making x the subject"for the range rearrange making x the subject
y=-1/(x+1)y=−1x+1
y(x+1)=-1y(x+1)=−1
xy+y=-1xy+y=−1
xy=-1-yxy=−1−y
x=-(1+y)/yx=−1+yy
y=0larrcolor(red)"excluded value"y=0←excluded value
"range "y in(-oo,0)uu(0,oo)range y∈(−∞,0)∪(0,∞)
graph{-1/(x+1) [-10, 10, -5, 5]}