square of sum
The well-known for squaring a sum of two numbers or is
It may be derived by multiplying the binomial by itself.
Similarly one can get the squaring for a sum of three summands:
Its contents may be expressed as the
Rule. The square of a sum is equal to the sum of the squares of all the summands plus the sum of all the double products of the summands in twos:
This is true for any number of summands. The rule may be formulated also as
which in the case of four summands is
One can use the idea of (3) to find the , when one tries to arrange the polynomial into the form of the right hand side (http://planetmath.org/Equation) of (3).
|Title||square of sum|
|Date of creation||2013-03-22 15:32:03|
|Last modified on||2013-03-22 15:32:03|
|Last modified by||pahio (2872)|