Tuesday

October 21, 2014

October 21, 2014

Posted by **Bailey** on Tuesday, June 16, 2009 at 10:08pm.

This is what i did:

x(2-x)+15<0

2x - x^2 + 15 < 0

-x^2 + 2x + 15 < 0

(x+3)(-x+15) < 0

-3<x<5

but when i check by subbing the number, say, 4 into x, the answer is always greater than zero. And the correct answer should be x<3 or x>5, which also seems wrong, because when i sub a number, say 2, into the inequality, the answer is still greater than 0.

what is wrong??? I've checked the things i did so many times and i don't see anything wrong????

- weird maths sum!! -
**bobpursley**, Tuesday, June 16, 2009 at 10:30pmLook at this:

(x+3)<0

x<-3

Not greater than.

-x+5<0

x>5

so x<-3 and x>5

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