√(81x^2 + x)− 9x
= (√(81x^2 + x)− 9x)(√(81x^2 + x)+ 9x)/(√(81x^2 + x)+ 9x)
= ((81x^2+x)-81x^2)/(√(81x^2 + x)+ 9x)
= x/(√(81x^2 + x)+ 9x)
= 1/(√(81 + 1/x)+ 9)
as x->∞, that becomes
1/(√81+9) = 1/18
Find the limit as x approaches infinity.
sqrt(81x^2 + x)− 9x.
I've worked this two different ways and have gotten 0 and 1/9, neither of which is the right answer according to the homework system??
1 answer
1 answer