Ddiiaabb

6 years ago

thx, but I don't understand why a=-3? (f(x) is contionuos, but what this help me to know a=-3)?!?

Mark Thong

6 years ago

Originally, f(x) = (x-2)(x+3)/(x-a) for x Hence when x --> a, denominator (x-a) --> 0,
which causes f(x) --> infinity , and f(x) becomes not continuous.

Therefore if a = -3
then for x which no longer contains (x-a) in the denominator that could render f(x) not continuous.

Jiayang

6 years ago

I think you should also explain why a cannot be 2.

Mark Thong

6 years ago

if a=2,
then when x--> a+ ,
it can be shown that f(x) --> infinity
and that would make f(x) not continuous.
hence a cannot be 2.

Ddiiaabb

6 years ago

thx :)