Question

why is (x-2)(x+1) > 0 = x>2 and X<1 ?

Answer 1

maybe this will help you

Answer 2

I can't open that Myin.

Answer 3

just draw the function and you will see
thats what i have in the pdf

Answer 4

When I see it I get it. But I wouldn't be able to understand the algebra...

Answer 5

(x-2)(x+1) > 0
x-2>0, x+1>0
x>2 x>-1

Answer 6

that's what I said nick but it's wrong. If x is greater than -1 you get a negative y value.

Answer 7

since it is of the form (x-a)(x-b)>0
then the roots will be x<a or x>b
hence it is x<-1 or x>2

Answer 8

For the function to be >0 (a positive number)
either: each bracket term must be +ve : x>2 AND x>-1 == x>2
or: each bracket term must be -ve: x<2 AND x<-1 == x<-1
so for f(x)>0: x must be <-1 or >2 but not anywhere between those two