Помогите букву а и б

Question

Помогите букву а и б

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Answer 1

A²-3a+1=7   a²-3a-6=0  

a²=6+3a  

a)  2a²-6a+2=12+6a-6a+2=14

б) a²(a²-3a+1)-3a(a²-3a+1)=a(a²-3a+1)(a-3)=a(6+3a-3a+1)(a-3)=7(a²-3a)=
7(6+3a-3a)=42