posted by Abi on .
I'm having a lot of trouble with solving inequalities and graphing them
solve the inequality and graph the solution on the real number line
I got SS: -infinity to -3 including -3 union -2 to infinity including -2
is that right?
EDIT WHERE INEQUALITY IS GREATER THAN OR EQUAL TO ZERO
do you mean
or do you mean
Sorry i should have put that in parenthesis
(x^2+x-6)/x greater than or equal to 0
well we know that when x = 0, it is -6/0
which is undefined but is huge positive for x small negative and huge negative for x small positive, so sketch that on your graph.
for x large positive x + 1 - (6/x) looks like y = x so draw a line sloping up at 45 degrees for large positive x
for x large negative x + 1 -(6/x) looks like y = x again so sloping down at 45 degrees in quadrant 3
Now, where is it zero?
x^2 + x - 6 = 0
(x-3)(x+2) = 0
x = -2 or x + +3
well, that does it, look at your graph sketch
it is positive from x = -2 to x = 0
it is positive from x = 3 to x = +oo
(x+3)(x-2) = 0
x = -3 or x = +3
positive from x = -3 to x = 0
positive from x = +2 to x = +oo
Isn't it x^2+x-6 = 0
(x+3)(x-2) = 0?
x = -3 or x= +2?
x = 3 or x = +2 I mean
x = -3 or x = +2
I ended up with SS: (-00,-3]union [2,00)
why would it be -3 to 0?
because it is zero at -3
then when x approaches zero from the left it is like -6/-.00000001 which is big positive
for example try x = -1
y = (1 + 1 - 6)/-1
I can not seem to type anything right tonight
y = (1 - 1 -6)/-1
See, this is where i have trouble understanding.
if i put if in the calculator i see why it'd be -3 to 0
but in the exams the professor makes sure we are not able to graph inequality in calculator
my graph was off on paper, i just verified on ti84+ and it looks different :-/
LOL try -3/-.001
No need for calculator
-anything over -anything is positive.
besides check when x = -1
which is between x = -3 and x = 0
Aww it's not funny, it's frustating! :(
you want me to replace x with -3
not sure what you're meaning by that try -3/-.001
where did you get the .001??
I'm so sorry i'm not understanding and thank you so much for helping
always check an easy point within the domain you are looking at.
I am saying what will happen when x = -.001 which is between x = -3 and x = 0
the answer you can see will be positive.
just about -6 / -.001
which is positive
I have not used a calculator.
yes, it gives me 6001.001 as an answer
You're not using a cal?
if i replace -.001 with x i get 6001.001
how are you solving that without calculator
but if replace x with -4 i get a positive answer too!
because if x = -.001
x^2 is tiny
x is tiny
-6 is -6
so we have -6/-.001 which is 6000
which is pretty much what your calculator says
I'm still not understanding...
it's okay i'll keep trying to figure it out.
im clearly not double checking it right since i checked for 1 and got a positive answer but its supposed to be negative till 2 :-/
thank you so much for your time!
it is honestly appreciated :)
if x = -4
(16 -4 -6) / -4
which is negative
If x = 1
(1 + 1 - 6)/1
You are welcome
Go back over all that and I bet you get it.
:D thank you!!!
I guess I've been staring at this for too long and probably not typing them correctly on the calculator!
THANK YOU SO MUCH!!!!!!
You are welcome, good luck with it. Forget the calculator and read that all carefully.