You might find it helpful to get used to translating back and forth between interval notation and plotting the sets on a number line with the endpoints either as closed or open circles depending on whether the endpoint is in the set. Once you're comfortable translating back and forth between interval notation and number lines, do a bunch of examples where you take two sets, plot them as number lines, figure out the union or intersection as a number line, then translate back to interval notation. Hopefully that will help you visualize what is occurring better.
NanoDegree: Intro to Self-Driving Cars (2019)
Coursera: Stanford Machine Learning (2019)
TESU: BA in Comp Sci (2016)
TECEP:Env Ethics (2015); TESU PLA:Software Eng, Computer Arch, C++, Advanced C++, Data Struct (2015); TESU Courses:Capstone, Database Mngmnt Sys, Op Sys, Artificial Intel, Discrete Math, Intro to Portfolio Dev, Intro PLA (2014-16); DSST:Anthro, Pers Fin, Astronomy (2014); CLEP:Intro to Soc (2014); Saylor.org:Intro to Computers (2014); CC: 69 units (1980-88)
PLA Tips Thread - TESU: What is in a Portfolio?
Coursera: Stanford Machine Learning (2019)
TESU: BA in Comp Sci (2016)
TECEP:Env Ethics (2015); TESU PLA:Software Eng, Computer Arch, C++, Advanced C++, Data Struct (2015); TESU Courses:Capstone, Database Mngmnt Sys, Op Sys, Artificial Intel, Discrete Math, Intro to Portfolio Dev, Intro PLA (2014-16); DSST:Anthro, Pers Fin, Astronomy (2014); CLEP:Intro to Soc (2014); Saylor.org:Intro to Computers (2014); CC: 69 units (1980-88)
PLA Tips Thread - TESU: What is in a Portfolio?
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