Language of Maths - MEI OCR topic

you need to know the names for the different types of numbers
counting numbers are positive whole numbers
natural numbers are the same but including 0
integers are all whole numbers (so including negatives)
rational numbers are fractions that have integers as the top and bottom number
real numbers are all rational and irrational numbers
and all the symbols for them but idk how to type those

and there's these arrows that i don't know how to type either but i'll try
so if you have two statements, x and y
x -> y means if x is true then y has to be true, but if y is true then x isn't necessarily true
x <- y is the same but the other way around
x <-> y (double ended arrow) means if one is true the other is always true and the other way around
that prob doesn't really make sense like that SO here's an example
n is 2 -> n is even
if n is 2 then it's definitely even, but not every even number is 2, so it only goes one way
n is a multiple of 5 <-> n ends in 5 or 0
there is no multiple of 5 that doesn't end in 5 or 0, and if a number ends in 5 or 0 then it is a multiple of 5, so the arrow goes both ways
there are questions in past papers that give you two statements and ask you to do the arrow, tbh i don't think it is common sense but then again i have none so maybe you would've been able to do it without being taught IDK

and the last thing is proofs
proof by exhaustion is where you test everything possible
so like if they tell you to prove that there is no square number from 0-100 that ends in 8 you can just write a list of all the square numbers within that range and be like yeah true
proof by deduction is proving something algebraically
proof by contradiction is showing what they said can't be true (either using algebra or i think just an example of a number that doesn't work is enough)

that's p much it
it's all in the textbook they explain it WAY better than me you should have a look!!
(but typing this up was good revision so thanks )

you need to know the names for the different types of numbers
counting numbers are positive whole numbers
natural numbers are the same but including 0
integers are all whole numbers (so including negatives)
rational numbers are fractions that have integers as the top and bottom number
real numbers are all rational and irrational numbers
and all the symbols for them but idk how to type those

and there's these arrows that i don't know how to type either but i'll try
so if you have two statements, x and y
x -> y means if x is true then y has to be true, but if y is true then x isn't necessarily true
x <- y is the same but the other way around
x <-> y (double ended arrow) means if one is true the other is always true and the other way around
that prob doesn't really make sense like that SO here's an example
n is 2 -> n is even
if n is 2 then it's definitely even, but not every even number is 2, so it only goes one way
n is a multiple of 5 <-> n ends in 5 or 0
there is no multiple of 5 that doesn't end in 5 or 0, and if a number ends in 5 or 0 then it is a multiple of 5, so the arrow goes both ways
there are questions in past papers that give you two statements and ask you to do the arrow, tbh i don't think it is common sense but then again i have none so maybe you would've been able to do it without being taught IDK

and the last thing is proofs
proof by exhaustion is where you test everything possible
so like if they tell you to prove that there is no square number from 0-100 that ends in 8 you can just write a list of all the square numbers within that range and be like yeah true
proof by deduction is proving something algebraically
proof by contradiction is showing what they said can't be true (either using algebra or i think just an example of a number that doesn't work is enough)

that's p much it
it's all in the textbook they explain it WAY better than me you should have a look!!
(but typing this up was good revision so thanks )

Just wondering, if you're taking AS maths this year, how are you revising for C2?

past papers!!
well i haven't done any yet but when i start revising that's what i'll do

Are you finding C2 ok? The only topic I actually understand is sequences and series, my teacher is the worst

i am finding none of maths ok but c2 is prob my worst
my teachers are good so i have no excuse lol but yours sounds AWFUL