Question

Whenever (x+5)(x-2)<0, which of the following expressions has a negative value?

(x^-4)-1

3x

x+4

x+3

x-3

Answer 1

the last choice is the answer.

Answer 2

how'd u arrive at that answer?

Answer 3

first find the interval to which the above inequality is satisfied.
What is that?

Answer 4

Think about it- the signs of (x+5) and (x-2) HAVE to be different for it to be <0.

Answer 5

if (x+5) is negative ----> (x-2) is definitely also negative
if (x-2) is positive ----> (x+5) is definitely also positive

Answer 6

1- because x has to 'try even harder to be negative' to make (x+5) negative than (x-2)
2- because x has to 'try even harder to be positive' to make (x-2) positive than (x+5)

Answer 7

henpen that is the longest method. It is better to use sign chart.

Answer 8

You just need to find values that
1-Doesn't make x+5 negative (i.e) x>-5
AND
2-Doesn't make x-2 positive (i.e) x<2

Answer 9

I know, but then you're just a mindless robot computing without knowing what's going on behind the equations