Question

Given that f(x)=x^2-6x-40/x^2-16 ,

then f(-4)=?

Answer 1

A) infty B) indeterminate C)7/4 or D)4/7

Answer 2

Given that f(x)=x^2-6x-40/x^2-16 ,

then f(-4)=?.

Replace every x with -4

Answer 3

16+24-40/16-16=0/0

Answer 4

@AbhimanyuPudi

Answer 5

Yeah good one.@zordoloom

Answer 6

There is a vertical asympote at 4. and a hole at -4.

Answer 7

I think the answer is C

Answer 8

Plot plot plot ...

Answer 9

It can't be c.

Answer 10

More like indeterminate.

Answer 11

Factorise the numerator
x^2-6x-40 = (x-10)(x+4)
x^2-16 = (x-4)(x+4)
So, f(x) = (x-10)(x+4) / (x-4)(x+4) = x-10/x-4
f(-4) = -4-10 / -4-4 = -14/-8 = 7/4

Answer 12

the answer is 7/4

Answer 13

please explain ?

Answer 14

i show you now\[\lim_{x \rightarrow -4} \frac{ x ^{2} -6x-40 }{ x ^{2}-16 }\]

Answer 15

@Rezz5 is correct. I totally forgot about limits.

Answer 16

now use L'Hopitals rule as putting -4 in both denominator and numerator we get zero, right?


su we can use L'Hopitals rule,


differentiate booth top and bottom we get...

\[\lim_{x \rightarrow -4} \frac{ 2x-6 }{ 2x }\]


now sub in -4 in the equation, and voila, we get 7/4,


if you dont understand tell me

Answer 17

thanks a lot.

Answer 18

welcome : )