a) x2 - 4x + 3
= x2 - x - 3x +3
= (x2 - x) - (3x -3)
= x(x - 1) - 3(x-1)
= (x-3)(x-1)
b) x2 - 5x +4
= x2 - x - 4x + 4
= (x2 - x) - (4x - 4)
= x(x - 1) - 4(x - 1)
= (x - 4)(x - 1)
c) x2 - 5x + 4
= x2 - 2x + 3x - 6
= (x2 - 2x) + (3x - 6)
= x(x - 2) + 3(x-2)
= (x + 3)(x-2)
d) x4 + 4
= (x4 + 4x2 + 4) - 4x2
= (x2 + 2)2 - (2x)2
= (x2 + 2 - 2x)(x2 +2 +2x)
a, = x\(^2\)- 2.2x + 4 - 1
= (x - 2)\(^2\)-1
b, = x\(^2\)- 4x + x + 2\(^2\)
= (x - 2)\(^2\)+x