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1. x^2 + 4x - 5 < 0

==> (x-1)(x+5) < 0

how do you define the values of x as : -5<x<1 (the correct answer)

do you not say

x - 1 < 0
x < 1

x+5 < 0
x < -5

But that's wrong? How do you arrive at the correct answer after factorising
2. x^2 + 4x - 5 < 0

==> (x-1)(x+5) < 0
hi there . basically after you've found out your x values . you then draw the graph in with the x values. you first think of the inequality as an equality.
as y=0 x will be 1 and also -5.
so then u draw in the graph and after that as it is y<0 you look at the y axis below not above , after that as this is a positive quadratic equation its a smiley face shape meaning it will be between -5 and one and also as it forms a semi circle type shape its within the range so
therefore x>-5 and x<1
3. (Original post by Feynboy)
x^2 + 4x - 5 < 0

==> (x-1)(x+5) < 0

how do you define the values of x as : -5<x<1 (the correct answer)

do you not say

x - 1 < 0
x < 1

x+5 < 0
x < -5

But that's wrong? How do you arrive at the correct answer after factorising
well when x = 1
(1-1)(1-5) = (0)(4) = 0
&
when x = -5
(-5-1)(-5+5) = (-6)(0) = 0

the < 0 is showing y<0
so you know from that info that when y<0
x is between -5 & 1

4. (Original post by Feynboy)
x^2 + 4x - 5 < 0

==> (x-1)(x+5) < 0

how do you define the values of x as : -5<x<1 (the correct answer)

do you not say

x - 1 < 0
x < 1

x+5 < 0
x < -5
Surely if both (x-1) and (x+5) are both negative then the product must be greater than zero, ie which is a contradiction.

So sketch a graph, put your roots down, and determine from there by looking for what x values the graph is less than 0.
5. (Original post by hashir7890)
...
First time I see snapchat being used as means of graph sketching...
6. (Original post by RDKGames)
First time I see snapchat being used as means of graph sketching...
lol

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