CMR

a) (a2-b2)2+(2ab)2= (a2+b2)2

b) (ax+b)2+(a-bx)2+c2x2+c2=(a2+b2+c2).(x2+1)

c) (a+b+c)3= a3+b3+c3+3.(a+b).(b+c).(c+a)

d) (a+b).(b+c).(c+a)=(a+b+c).(ab+bc+ca)-abc

e) ab.(a+b)-bc.(b+c)+ac.(a-c)=(a+b).(b+c).(a-c)

f) 2bc.(b+2c)+2a.(c-2a)-2ab.(a+2b-7abc)= (b+2c).(c-2a).(a+2b)

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