The sum of two numbers is 51 and the difference is 9. What are the numbers?
2 answers:
we dont know what is the two numbers so let us assume that one is x and other is y
so the sum of two numbers will be x+y which is equal to 51
and their difference is 9
so now we have two equations we can solve this by elimination method.
we know that we have -y and +y which is same value with opposite sign so we can cancel it and x+x will be 2x and 51+9=60
we can plug x=30 in any one of the equations
You might be interested in
f(x) is the same as y, so we can say y = f(x)
Writing f(x) < 0 means we want to find when y < 0.
Visually, we are looking at the graph when the curve is below the horizontal x axis.
This is the portion in red that I have marked in the diagram (see attached image below). I apologize for the numbers being blurry.
The left red portion is from negative infinity to -3. In terms of a compound inequality we write which in interval notation is
. The curved parenthesis tells the reader to exclude both endpoints.
The right red portion is from x = -1.1 to x = 0.9, excluding both endpoints. So we say which becomes the interval notation
. This is not ordered pair notation even though it looks identical to it.
-------------
<h3>Answer in interval notation:The "U" means "set union" which glues together the two separate intervals. Basically it's saying "x is either in the interval (-infinity, -3) or it is in the interval (-1.1, 0.9)"
