Explanation:
Unitary method
The unitary
method is a technique in elementary algebra for solving a class of problems in
variation. It consists of altering one of the variables to a single unit, i.e.
1, and then performing the operation necessary to alter it to the desired
value. (Our
solved example in mathguru.com uses this concept)
For example, to solve the problem 'A man walks seven miles in two
hours. What is his average speed?' we aim to calculate how far the man walks in
one hour. We can safely assume that he would walk half the distance in half the
time. In one hour (one half of two hours) he walks three and a half miles (one
half of seven miles). His speed is therefore three and a half miles per hour.
We can apply the same method to the problem 'A man walks at four
miles per hour. How long would it take him to cover five miles?' by asking
first, how long does the man take to walk one mile. One is a quarter of four,
so it takes him a quarter of an hour to walk one mile. To walk five miles it
therefore takes him five quarter hours, or an hour and a quarter.
http://en.wikipedia.org/wiki/Unitary_method
Inequality (mathematics)
In mathematics, an inequality is
a statement how the relative size or order of two objects or about
whether they are the same or not
1. The
notation a < b means that a is less
than b.
2. The
notation a > b means that a is greater
than b.(Our solved example in mathguru.com uses this concept)
3. The
notation a ≠ b means that a is not
equal to b, but does not say that one is greater than the
other or even that they can be compared in size.
http://en.wikipedia.org/wiki/Comparison_(mathematics)
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