- #1
turdferguson
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- 0
Homework Statement
Im not good with latex, but I am having trouble with the limit as x approaches -1 of
[sin(x2+3x+2)]/(x3+1)
The Attempt at a Solution
Ive tried substituting u = x2+3x+2 but I keep getting -1/4 instead of the correct limit 1/3
by long division, x3+1 = (x2+3x+2)(x-3) + 7x + 7
This yields the limit as u approaches 0 of
[sin(u)]/[u(x-3) + 7x + 7]
after simplifying sinu/u, I get the limit as u approaches 0 of
1/[x - 3 + (7x+7/u)] = u/[u(x-3) + 7x+7]
If I plug in x=-1, the limit is -1/4, not 1/3. What am I doing wrong?