Wtf is the difference between (-∞,5) and [-∞,4] ?

[eqn]\left\{-\infty\right\}\,\cup\,\left(4,\,5\right)[/eqn]

the first is numbers smaller than 5
the second is numbers smaller or equal to 4, and including -infinity

The second isn't a set of real numbers because it includes -∞.

>>9122885
Yeah it has to be an error, but if op meant (-inf,4] then the difference would just be the former set is larger by (4,5)

u can't have closed bracket infinities retard

>>9122911
>u can't have closed bracket infinities retard
Speak for yourself, brainlet
https://en.wikipedia.org/wiki/Extended_real_number_line

>>9122876
0.999...

>>9122913
>fake bullshit
stay in your cuckshed math major. for real people infinity isn't a number.

>>9122918
>stay in your cuckshed math major. for real people infinity isn't a number.
do you have trouble reading, brainlet? infinity is a number for extended real people

>>9122918
I think more 'ordinary people' would consider infinity a number than mathematicians desu

Draw a number line and do some coloring

I learned in calculus that, for either infinity, you can only have parentheses closing them; not a bracket.

EX:
(-infinity, 5)
(-infinity, 4)
[3, infinity)

Brackets usually mean "up/down to and including" in calculus too, so it wouldn't make sense to say, for [-infinity, 4], "from 4 down to and including neg. infinity" since infinity isn't a number. You can't "include" endless increase or endless decrease like you can "include" a discreet number.

This is just from what I've remembered from a super basic, first-day lecture of calculus I though.

>>9123551
see
>>9122913

>>9122876
>Wtf is the difference between (-∞,5) and [-∞,4] ?
(-∞,5) + [5,4] = (-∞,4]

>>9122876
>(-∞,5)
x < 5

>[-∞,4]
x =< 4
This is also syntactically incorrect, you can't really have a closed bracket for -∞ and ∞

>>9123610
>This is also syntactically incorrect, you can't really have a closed bracket for -∞ and ∞
see
>>9122913

>>9123612
Yes, but for the scope of the course OP is taking, the closed bracket for -∞ and ∞ is incorrect.

>>9123617
How do you know what course he/she is taking?

>>9123619
you learn about domains and ranges during MAT1033 and MAC1107. Not knowing the meaning of inequalities like what OP posted suggests that OP has not reached precalculus.

>>9123625
>MAT1033 and MAC1107
literally what

>>9123627
intermediate algebra and college algebra.

>>9123634
>college algebra.
You mean rings, groups, fields, etc.?

>>9123664
No, like

>Solve polynomial, rational, exponential, and logarithmic equations.
>Solve equations involving radicals.
>Solve equations with rational exponents.
>Solve equations with negative exponents.
>Solve polynomial and rational inequalities.
>Use the Fundamental Theorem of Algebra and the Conjugate Zeros Theorem to find zeros of polynomials of degree three or greater.
>Find the vertex of a parabola and the center and radius of a circle by completing the square.
>Find the vertex of a parabola written in standard form by using the formula h = -b/2a.
>Convert an exponential equation to logarithmic form, and a logarithmic equation to exponential form.
>Evaluate exponential and logarithmic functions using the change of base formula and a calculator.
>Use the properties of logarithms to expand a logarithmic expression, and to write an expanded logarithmic expression as a single logarithm.
>Solve a system of linear equations using Gaussian elimination.
>Solve a system of linear equations using matrix inversion or Cramer’s Rule.

>>9123691
All of those except the last 3ish were taught in my hs calc classes for some stupid ameriburger reason

>>9123711
I tutor this stuff on fridays at my uni. If you did well in high school, then thats great, well done. I had to start from the bottom cuz I wasn't a very good student in high school.

>>9122876
The first is correct notation and the second is gibberish.

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203KB, 798x1200px

>not working in the projective real line
I shig at you brainlets

>>9122876
Second one includes 4.1, 4.2, 4.6, 4.8, 4.999, 4.999999, 4.9999999999 etc

>>9123955
EDIT: meant first one