a) 4x2 - y2 + 4x + 1 = 4x2 + 4x + 1 - y2
= ( 2x + 1 ) 2 - y2
= ( 2x + 1 - y ) ( 2x + 1 + y )
b) x3 - x + y3 - y = x3 + y3 - x - y
= ( x + y ) ( x2 - xy + y2 ) - ( x + y )
= ( x + y ) ( x2 - xy + y2 - 1 )
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a. 4x2−y2+4x+14x2−y2+4x+1 =(4x2+4x+1)−y2=(2x+1)2−y2=(4x2+4x+1)−y2=(2x+1)2−y2
=(2x+1+y)(2x+1−y)=(2x+1+y)(2x+1−y)
b. x3−x+y3–yx3−x+y3–y =(x3+y3)−(x+y)=(x+y)(x2−xy+y2)−(x+y)=(x3+y3)−(x+y)=(x+y)(x2−xy+y2)−(x+y)
=(x+y)(x2−xy+y2−1)
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