find limit: limit of x approaching -8
(x^2+3x-40)/(x+8)

Question

find limit: limit of x approaching -8 
(x^2+3x-40)/(x+8)

anonymous · Answer

can you use the L'Hopital's rule here? It should be since the denom is 0 at the limit

amistre64 · Answer

IF x=-8 has a finite value, it will cause the top to equal zero. in other words,  if (x^2+3x-40) = (x+8)(....)  then they both zero out and it has a hole at -8 that can be filled in

anonymous · Answer

or you can factorize the numerator and cancel the factor common to numerator and denominator. you will get the same answer

amistre64 · Answer

x^2  +3x -40
        0       -8x +40
-8    x        -5     0

the good news is that it does factor, therefore to fill in the hole we can use the equivalent equation of:  x-5

anonymous · Answer

@robtobey you copied the problem wrong. The denominator is 8+x and not 8x.

anonymous · Answer

$$\lim_{x \rightarrow -8} \frac{ x^2+3x-40 }{ x+8 }=\frac{ (x+8)(x-5) }{x+8}=x-5=-13 $$