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CCSS.Math:

in the following table is why a function of X in order for y to be a function of X for any X that we input into our little function box so let's say this is y as a function of X it needs to spit out at an only only one value of y if it spit out multiple values of Y then it might be a relationship but it's not going to be a function so this is a function this is a function if we had a situation where if we input X into a box it could be multiple possible Y's than this is not not a function so let's think about this table right over here what X is equal to 1 we get Y is equal to 1 but when X is equal to 1 again all of a sudden Y is equal to 2 so here we have a situation where we input 1 into our little relationship box and when we input 1 for our relationship box we could get a 1 or we could get a 2 for y so this is definitely not a function for any input into a function it has to map to exactly one output here it's mapping to two outputs so this is not a function