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Mathematics 13 Online
MARC:

The function f is defined by

MARC:

\(f:x \rightarrow x^2-x,x \in~\mathbb{R}\)

MARC:

State whether f is one-to-one,giving a reason for the statement.If the domain of f is restricted to the subset of \(\mathbb{R}\)

MARC:

for which

MARC:

\(x\ge~k\) find the least value of k for which f is one-to-one.

MARC:

Answer: No. f(0)=f(1)=0

MARC:

Not sure how to do next..

MARC:

find the least value of k for which f is one-to-one.

Angle:

I am confused .-.

MARC:

okay.. xD r u confused with the question or my answer ?

Angle:

very confused by the question and I think the answer might be wrong

Angle:

nvm answer is right

Angle:

-> find where the function is one to one? there is only one value...

MARC:

do u hv any hints? ^

MARC:

is the answer 1/4 ?

Angle:

hmmm f(1/4) = (1/4)^2 - (1/4) = 1/16 - 1/4 = 1/16 - 4/16 = -3/16 f(3/4) = (3/4)^2 - (3/4) = 9/16 - 12/16 = -3/16

Angle:

but close ;)

MARC:

okay,let me try.. (:

Angle:

the dot I drew should be the only one-to-one point in this function |dw:1480912296146:dw|

Angle:

excuse my horrible drawing skills x'D

MARC:

it's okay..it's better than my drawing.. xD

Angle:

basically, this function is symmetrical so the one point that is alone without a repeated y value would be the middle point the repeated points each have their evil twin the same distance from this middle point you have pointed out that f(0) = f(1) and so the middle point would be the middle of those two values do you have a better guess now? ;)

MARC:

I think i got it

MARC:

is it x=1/2

Angle:

mhmm ^_^ thanks what I think your answer should be although it was really confusing the way they asked it >.>

Angle:

*that is what I think

MARC:

i use the completing the square method to find the value based on ur diagram

Angle:

uhhh you could have just done (1 - 0)/2 = 1/2 because you found that f(0) = f(1) and the middle point should be the perfect middle of those two...

MARC:

xD

MARC:

xD

Angle:

but completing the square works too x'D

Angle:

it's just more work .-.

MARC:

Thank you! @Angle ^_^

MARC:

agree with u @Angle x'D

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