# Factoring of polynomials

In general case factoring of a polynomial is not always possible. But there are some cases, when it can be executed.

 1 If all terms of a polynomial contain as a factor the same expression, it is possible to take it out of  brackets (see above). 2 Sometimes grouping terms of a polynomial into brackets, one can find a common expression inside the  brackets, the expression may be taken out of the brackets as a common factor, and after this the same expression will be inside all brackets Then this expression must also be taken out of the brackets and the polynomial will be factored. E x a m p l e : ax + bx + ay+ by = ( ax+ bx ) + ( ay + by ) = = x ( a + b ) +  y ( a +  b ) = ( x + y ) ( a +  b ) . 3 Sometimes including of new, mutually cancelled terms, helps to factor a polynomial. E x a m p l e : y 2 – b 2 = y 2 + yb – yb – b 2 = ( y 2 + yb ) – ( yb + b 2 ) = = y ( y + b ) – b ( y + b ) = ( y + b ) ( y – b ) . 4 Usage of the formulas of abridged multiplication.