Is the relation {(2,5), (0, -5), (-2, 6), (2, 3)} a function?

Consider the function f(x)=-5x+3 what is f(-2)

One number is 4 less than 3 times a second number. if 3 more than two times the first number is decreased by 2 times the second number, the result is 11. use the substitution method. what is the first number?

Idon't want to fail summer school. the probabilities of contamination in medicine capsules due to the presence of heavy metals and different types of microbes are given in the table. the probability of capsule b having microbial contamination is (the same as, greater than, less than) the probability of capsule d having it.