a. x² + 7x + 5x + 35 = ( x² + 7x) + ( 5x + 35) = x·( x +7) + 5·( x +7) =
= ( x +7)·( x +5)
b. x² - 6x - 8x + 48 = ( x² - 6x) + ( -8x + 48) =
= x· ( x -6) - 8·( x -6 ) = ( x -6) ·( x -8 )
c. x² + 2x - 7x -14 = ( x² + 2x) + ( -7x -14) =
= x· ( x +2) - 7·( x + 2) = ( x +2)·( x -7)