Celestial09 wrote:
Hi!
A small doubt..
x(x-2)>0
x>2 and x,0...
but is it not x>2 and x> 0?
why inequity sign changed in second while comparing to zero?
thanks
any imp theory link you like to share please...
I'm happy to answer your doubt, regardless of the question. I will answer it as we solve inequality.
What does it mean X(X-2)>0 ? Let's put it in simple way.We have TWO number A & B are multiplied and result Bigger than 0. When does Happen? From NUMBER PROPERTIES:
Case 1: A = positive & B= positive ............ A * B >0
Case 2: A =negative & B= negative ............ A * B >0
Let look to our inequality :
X(X-2)>0Put: A=X & B= X-2Using cases mentioned above let's analyze our inequality:
Case 1:
X (X-2)>0.......... Remember A & B positive means A >0 & B>0
X>0 & X-2>0 then
X>2 ....... Can you come up with example that satisfy that X>0 & X>2 in same time???Answer:YES we can. Any number BIGGER than 2 does so
CASE 1 yields that X>2 Case 2X (X-2)>0.......... Remember A & B negative means A <0 & B<0
X<0 & X-2<0 then
X<2........Can you come up with example that satisfy that X<0 & X<2 in same time???Answer:YES we can. Any number SMALLER than 0 does so.
CASE 2 yields that X<0 From above Cases we can conclude FINALLY that: TO SATISFY the Inequality:
Either X<0 or X>2................NOTICE that when we combine TWO CASES, we use 'Either......OR......'
You can check number if you are in doubt.
I will expand my explanation about how to solve if you face this question:
X (X-2)<0From NUMBER PROPERTIES:
Case 1: A = positive & B= negative ............ A * B <0
Case 2: A =negative & B= positive ............ A * B <0
Put: A=X & B= X-2Using cases mentioned above let's analyze our inequality:
Case 1:
X (X-2)<0.......... Remember A = positive means A >0 & B=negative means B<0
X>0 & X-2<0 then
X<2 ....... Can you come up with example that satisfy that X>0 & X<2 in same time???Answer:YES we can. Any number BIGGER than 0
& SMALLER than 2. We can put mathematically as
0<X<2. For example X=3/2
CASE 1 yields that 0<X<2 Case 2X (X-2)>0.......... Remember A = negative means A < 0 & B=positive means B>0
X<0 & X-2>0 then
X>2........Can you come up with example that satisfy that X<0 & X>2
in same time???Answer:NO, we can NOT. It means that we need a number that is negative and positive in same time. Can you find it?
CASE 2 yields no solution From above Cases we can conclude FINALLY that: TO SATISFY the Inequality:
0<X<2Check numbers if you want.