# functions (1 Viewer)

#### kkk579

##### Well-Known Member
in qs like these why is it when we have equations like “f(x)=16 if x<-3” the range is put in a square bracket although the inequality sign isn’t <= or =>??

i thought u only put square brackets when it’s <= or =>

for example “f(x)=5-x of x<-2” and “f(x)=-x^2-1 for x<0” uses normal brackets since they use < or > and not <= or =>. this makes sense as to why they use normal brackets but why are horizontal lines exceptions???

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#### kkk579

##### Well-Known Member
is it because it’s a straight line that means y would be = to 16 anyways so although the equation doesn’t state that it’s <= or => u can directly assume it??
if that makes sense

#### Life'sHard

##### Well-Known Member
in qs like these why is it when we have equations like “f(x)=16 if x<-3” the range is put in a square bracket although the inequality sign isn’t <= or =>??

i thought u only put square brackets when it’s <= or =>

for example “f(x)=5-x of x<-2” and “f(x)=-x^2-1 for x<0” uses normal brackets since they use < or > and not <= or =>. this makes sense as to why they use normal brackets but why are horizontal lines exceptions???
I think you need to reword some of this and give direct answers instead of being ambiguous and saying "in a square bracket" there are multiple square brackets lol. What is the range for f(x) = 16 etc? Might just be me but I'm kinda confused about what you're asking?

#### kkk579

##### Well-Known Member
I think you need to reword some of this and give direct answers instead of being ambiguous and saying "in a square bracket" there are multiple square brackets lol. What is the range for f(x) = 16 etc? Might just be me but I'm kinda confused about what you're asking?
square bracket ——> [ ]
i have attached an example of a q down below
my q was basically why do we write the range of f(x)=16 if x<-3 like [16, 16] if the inequality sign is not >= or =<.
is it because it’s a straight line so we can directly assume y=16 which is why we write in in [ ] instead of ( )

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#### kkk579

##### Well-Known Member
square bracket ——> [ ]
i have attached an example of a q down below
my q was basically why do we write the range of f(x)=16 if x<-3 like [16, 16] if the inequality sign is not >= or =<.
is it because it’s a straight line so we can directly assume y=16 which is why we write in in [ ] instead of ( )
in short why is the range written as [16,16] and not (16,16)

#### Life'sHard

##### Well-Known Member
in short why is the range written as [16,16] and not (16,16)
Oh ok the reason why you're able to take on 16 is because other values of x will give you the result of 16. So although at f(-3) ≠ 16, when x = -4,
f(-4) = 16 meaning 16 exists in the "range" of the function hence square brackets. It's kinda weird how they considered [16,16] a range cause it's really just a point lol.

#### kkk579

##### Well-Known Member
Oh ok the reason why you're able to take on 16 is because other values of x will give you the result of 16. So although at f(-3) ≠ 16, when x = -4,
f(-4) = 16 meaning 16 exists in the "range" of the function hence square brackets. It's kinda weird how they considered [16,16] a range cause it's really just a point lol.
i’m kind of confused why did u use -3 and -4
also what do u mean by existing in the range

#### Life'sHard

##### Well-Known Member
i’m kind of confused why did u use -3 and -4
They're just example cases as to why 16 will exist in the range even though it doesn't exist at x = -3.

• carrotsss

#### kkk579

##### Well-Known Member
They're just example cases as to why 16 will exist in the range even though it doesn't exist at x = -3.
but why do we use square brackets instead of normal brackets???
sorry i’m just vv confused

#### Life'sHard

##### Well-Known Member
but why do we use square brackets instead of normal brackets???
sorry i’m just vv confused
If 16 exist in the range of the function then use []

If not exist use ()

I have proven that 16 exist by taking the case of x = -4.

Therefore, use square brackets.

• carrotsss