Answer:
D
Step-by-step explanation:
If we isolate the variable in each given compound inequality, we can quickly realize that D is correct.
x is less than or equal to four (solid point on 4 with line going left), but greater than -1 (open point going right).
Signs with 'or equal to' have solid points, and signs without are not solid.
I hope this helps!
All the numbers in this range can be written as
with
and
. Construct a table like so (see attached; apparently the environment for constructing tables isn't supported on this site...)
so that each entry in the table corresponds to the sum of the tens digit (row) and the ones digit (column). Now, you want to find the numbers whose digits add to perfect squares, which occurs when the sum of the digits is either of 1, 4, 9, or 16. You'll notice that this happens along some diagonals.
For each number that occupies an entire diagonal in the table, it's easy to see that that number
shows up
times in the table, so there is one instance of 1, four of 4, and nine of 9. Meanwhile, 16 shows up only twice due to the constraints of the table.
So there are 16 instances of two digit numbers between 10 and 92 whose digits add to perfect squares.
Answer:
r+3
Step-by-step explanation:
r is an expression. To get an expression that is 3 more, just add 3
r+3
