Which comes first domain or range
2 answers:
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You must try to remove one of the unknown variables from the system by multiplying one in a way that when adding (or subtracting) one to another “makes it disappear” and so whatever value you get can be substituted back in to get the other unknown!
Answer:
I assume you know Arithmetic Progression .
so, we have to find the first and last 4-digit number divisible by 5
first = 1000 , last = 9990
we have a formula, = a + (n-1)d
here, is the last 4-digit number divisible by 5.
n is the number of 4-digit even numbers divisible by 5
d is the common difference between the numbers, which is 10 in this case
a is the first 4-digit number divisible by 5
9990 = 1000 + (n-1)*10
899 = n-1
n = 900
Hence, there are 900 4-digit even numbers divisible by 5